Last year I participated in a fruitful Academia.edu session on loanwords from Turkic into Samoyedic. I am now honored to see that the final article — P. S. Piispanen 2018, Turkic lexical borrowings in Samoyed, Acta Linguistica Petropolitana 14(3) — ends up incorporating + crediting in detail several of my suggestions. 
I would like to add here some detail on one of my four views to have made it into the paper. Footnote 4 mentions my proposed date of as far back as 3000 years of age (= 1000 BCE) for Proto-Samoyedic. This is not directly built on just my WIP database of Proto-Samoyedic though: it’s also informed by morphology and phonology. 
Samoyedic does seem to be the most internally lexically divergent branch of Uralic. We often find native Uralic roots continued in just 1-2 languages,  in contrast to the situation elsewhere in Uralic, where a native Uralic etymology also predicts good dialect distribution. This fact alone could probably be explained as some kind of a serial-substrate effect though: suppose substrate 1 in Proto-Samoyedic leaves an effect of replacing some Uralic core vocab, substrates 2a and 2b some more in Proto-Selkup and common Northern Samoyedic, some third-generation substrates still some more in Nenetsia, Taimyr, etc.
But it is also the case that Samoyedic is clearly divided in at least six branches with clear boundaries of intelligibility between them. This is quite different from all the other eight Uralic “main” branches, which all show dialect-continuum structure. Maybe the only other really clear within-branch language boundaries are Livonian vs. rest of Finnic, and Udmurt vs. Komi (although also later dialect shuffling has created other opaque language boundaries like Northern vs. Skolt Sami, or Standard Finnish vs. Standard Estonian). In Samoyedic, although there is a base layer of some old crisscrossing isoglosses, and probably late areally shared phenomena, all six of the Samoyedic groups also have a large share of unique distinguishing innovations. E.g. in consonant phonology:
- Nenets(ic): *nt > n
- Enets: *-C > -ʔ (general)
- Nganasan: *ŋt > jt
- Selkup: *j *w > *ć *k
- Kamassian: *NP > *NN (general)
- Mator: *kʲ × *sʲ > k
This selection is also not at all unique. Similar lists could be built also of solely vowel phonology, or inflectional morphology, derivational phonology, core vocabulary, loan vocabulary, notable semantic shifts — pretty much any one component of language. This is the key point that I see putting Samoyedic one “grade” ahead of the historical development of the other subgroups of Uralic. Within a group like Finnic or Khanty, no obvious taxonomy of this sort is possible. We can chart out a bunch of prominent local innovations (Western Finnish *ð > r, Southern Khanty *ɬ⁽ʲ⁾ > t⁽ʲ⁾…), but usually not even cover the dialect area by these, let alone divide it. There are always transitional dialects either lacking or overrepresenting putative branch-defining innovations. More damningly yet, in dialect continuum cases there’s not much coherence between the “phonological branching”, “morphological branching” etc. E.g. the plural genitive isogloss across Finnic (west *-den ~ east *-i-den) ends up being just one isogloss among a dozen or so that have been proposed as grounds for a primary division of the group.
Quite feasibly transitional Samoyedic varieties once did exist, but died out eventually, due to other groups such as Russians, Yakuts, Evenkis enroaching on the rather extensive Samoyed area; or due to “secondary expansions” within the family itself. (Yurats works as a proof-of-concept, assimilated to Tundra Nenets rather than Russian.) This does not make for a counterargument, though, since we by now see the same process playing out within the “younger” groups as well: all but Northern Mansi is gone, Southern Khanty is gone, Kemi and Akkala Sami are gone; Ume, Pite and Sea Sami are moribund, Votic and Ingrian are moribund; many traditional Finnish and Estonian dialects are rapidly assimilating into the standard. Assuming that the Samoyedic expansion ran out of steam (turned into a recessive, low-status language family) much faster than others sounds unwarranted too, especially given that it has in the end reached a much wider area than the other Uralic subgroups.
We do not have any historical-philological evidence for dating the early stages of Samoyedic. But we can do the same with Samic and Finnic, by leveraging the well-known history of Germanic (and even Latin) through loanword evidence. The results come out, in both cases, as showing that the first isoglosses within S and F start appearing already in the second half of the first millennium BCE, and clear dialect areas have been established by 0 CE, though many common innovations continue to diffuse across the dialect area until as late as the first major round of Slavic influence circa 1000 CE.  We know dialect continua can fracture into multiple clearly distinct languages quite rapidly (most of Finnic was still a single dialect continuum circa 1900, and is looking headed for just a handful of surviving discrete daughter languages by 2100) — but we also know Samoyedic was “discrete” already as early as about 1800. As a conservative estimate, I’d therefore then add about 400 years more age for Samoyedic. This adds up to a minimum age of about 2600 years BP for Samoyedic, which I then round up to the accuracy of one decimal, due to the numerous uncertainties involved.
This is all still a lower age limit. The only real upper limit seems to be that Samoyedic was still a single dialect continuum by the time of contact with Proto-Turkic, usually dated somewhere around 0 CE… but “standing” dialect continua can easily reach ages of a millennium or two! So 3000 BP really isn’t even a maximally bold suggestion. A pitch like 4500 BP would however start to have further implications: I’d obviously also have to backdate Proto-Uralic closer to the traditional 6000 BP than the recently proposed “shallow” chronologies branching off only at about 4000 BP.
Proto-Samoyedic also seemingly shows substantial general divergence from Proto-Uralic, but this does not mean that a “long” chronology would demand an outright Mesolithic dating for PU. Again as seems to be the case also in Samic and Finnic, various pan-Samoyedic innovations could be also re-dated into their common dialect continuum phase. Helimski’s vowel system updates (retained *a, *ä, *e in PSmy rather than Janhunen’s *ä, *e, *i) already point in this kind of a direction, as does the phenomenon of native Uralic roots being often restricted to a single Samoyedic language (this means that many may have been lost in parallel in all). I think two likely additional candidates are the sound change *ľ > *j, found even in isolated loans from Tungusic; and “coaffix insertion” into the local cases, which has been long known to have proceeded differently in Nganasan than in the rest of Samoyedic (and as I’ve recently learned from Valentin Gusev, Nenets and Enets have some quirks in this too in the possessed paradigm).
I will readily admit that none of the above discussion takes any direct archeological evidence into consideration. Again (cf. footnote 2), this is intentional. Archeology cannot date languages, not even identify them: it can only create a sociohistorical backdrop that we can attempt to pin language expansions on. At a pinch, all that really happens here is that we draw one directed graph indicating known relationships of archeocultural descent and influence; another directed graph indicating known linguistic relationships; and attempt to fit the latter as a minor of the former. If culture A begets B which begets C, a priori it would not be parsimonious to assume A, B and C to have all spoken different languages entirely; but it may also prove necessary to fit other pieces of the big picture in. If the proposed language of culture B has clear contact influence from language L, we’d like to assign also L to have been spoken in a culture that was actually in contact with B. Everything else, e.g. cultural reconstructions on Proto-Samoyeds as copper traders or reindeer nomads or hunter-gatherers or what have you, comes downstream of linguistics/archeology pairings based on the “topology of chronology”.
The recent decades’ paradigm shift on the origins of Finnic and Samic is again instructive, I think. The same language expansions were varyingly pinned on multiple known material-cultural expansions, with details filled in with assumptions where necessary. What had changed was not the archeological evidence: the new picture emerged due to new linguistic evidence, with results such as the early divergence of South Estonian and Livonian, the existence of a para-Sami substrate across most of Finland and far east into Russia, and the unviability of a common Finno-Samic node (itself done in maybe primarily by loanword research showing many “Finno-Samic lexical innovations” to be loans back-and-forth, or in parallel from Indo-European). These changed the topology of the Uralic linguistic family tree enough that it could no longer be fit into the “archeological family tree” in the same location.
And for Samoyedic, we don’t have a clear enough picture of this area of the family tree yet. There’s no consensus model for the branching of Samoyedic, nor for its splitting from Uralic. Those who side with an East Uralic group will be able to find a roughly suitable archeological assignment for it; so will those who side with a Finno-Ugric group; etc.
The fact that language does not have to coincide exactly with culture also helps to create a lot of wiggle space here. For one, linguistic descent can happen also through cultural “contact”, rather than cultural “descent”; for two, linguistic splits can happen invisibly, without any corresponding cultural split (especially if we’re talking about just basic dialect diversification); for three, cultural expansions can pull along multiple linguistic lineages at the same time. The last two in particular combine to form a situation where even if we could match cultural and linguistic lineages accurately, we still cannot use splits in one to date the splits in the other. I believe this is indeed the case in Samoyedic. There is strong archeological evidence to assume that Northern Samoyedic arrived on the Arctic coast only in the ballpark of 1000 years ago;  but this does not allow us to conclude that the language spoken at the time was really unified Proto-NSmy. I would think that at minimum a pre-Nganasan dialect and a pre-Nenets-Enets dialect already existed separately at this time, to allow for certain cases where Nenets-Enets shares isoglosses with southern Samoyedic branches like Kamassian or Mator. Perhaps more varieties yet, existing first as clan or family dialects before ballooning into full-blown languages.
I do not believe I am ending up with a radically different approximation for the age of Samoyedic from previous researchers — e.g. Janhunen in his 1998 handbook article guesstimates that “proto-Samoyedic seems to have dissolved as recently as the last centuries BCE”, i.e. in the same millennium as my conservative assumption does (or, for what it’s worth: Blažek’s recent glottochronological calculation comes out at 250 BCE). But as comes to the deeper end, I do make one methodological basic assumption that I do not think other linguists always properly appreciate: a proto-language is by definition unitary, and it is broken up already by the first emerging dialect isogloss. Not upon the emergence of more major division lines such as daughter ethnicities (identities are malleable and can easily also re-coalesce), or “language-type” rather than “dialect-type” boundaries (whatever that may mean), or loss of mutual comprehensibility (not a binary distinction anyway). A proto-language only has its strong methodological value if it is reserved for the truly common ancestor, a stage that precedes the rise of all areal variation; otherwise we lose the ability to reconstruct innovations, and can always appeal to almost any arbitrary modern variation having “already existed in the proto-language” (so, ever since humans first invented speech?). All isoglosses have a finite age, and when we seek to date a family’s break-up, we are seeking to date the oldest isogloss observable within the family — or at least, the oldest theoretically somehow dateable isogloss. And it is these roots that I believe could run quite deep compared to the conservative approximations.
 Really I wonder if I should start keeping a list of publications I have been credited on. Eventually this would be pointless I’m sure, but as an early-career researcher, maybe not…
 Comparative syntax, especially clause-level, I must admit I know roughly jack shit about (in general, not just re: Samoyedic). This is an intentional omission of effort: maybe my core subfield is comparative phonology, which does not have much overlap with syntax at all. At most there would be third-degree repercussions through morphology / classification / areal linguistics, hardly any more than from fields like paleography or folkloristics.
 Examples (far from an exhaustive list): PU *uwa ‘flow’, *kuwakka ‘long’ reflected only in Nganasan; *ekä ‘big; father’ only in Enets; *muja- ‘to smile’, *säńćä- ‘to stop’ only in Nenets; *kajə ‘hair’, *këččə ‘bitter’ only in Selkup; *porə- ‘to eat’, *suwďa ‘finger’ only in Mator. Works the other way too: I’ve a list of the most widespread Uralic vocabulary, and their average distribution across Samoyedic, when present, seems to be clearly lower than across any other branch.
 I may do a fuller post on this eventually, but I believe the supposed “Slavic loanwords in Proto-Finnic” like *pappi ‘priest’, *risti ‘cross’ well postdate the breakup of PF. Several other loanwords from essentially the same phase of Slavic already show dialect divisions existing: mainly via differing sound substitutions, such as *netäli ~ *nätäli ‘week’, *värttinä ~ *värttenä ~ *värttänä ‘spindle’, *šauki- ~ *šaukë- ‘pike’. A few cases like ‘priest’, ‘cross’ may appear uniform just due to their phonological simplicity, therefore making up a case of what I call “convergent parallel loans“.
 Dated more accurately actually, but I do not have the details on hand.