The Ket link has been well accepted. Basque is another story. Like I said, if anyone wants to prove the link, show the grammatical correspondence with a convincing and systematic set of sound changes one to the other—not just a few similar roots.
I don’t care for much of the research on transoceanic contact if it’s based on superficial commonalities: “Hey look...here’s a design motif that looks like this design motif.” That said, anyone not keeping an open mind as to such contacts is being rash. There was a Bishop of Gardar who was said to be going to Markland/Vinland and was never heard from again...that was in the early 1300s. There are also casual reports of Norse ships bringing timber from those areas round about the same time.
What I mean is no one’s found an Irish settlement comparable to L’Anse aux Meadows. All we have is Norse testimony—which is intriguing and perhaps even accurate, but not solid proof.
The main obstacle over the past century or so — and around 1900 the PreColumbian Viking presence was generally accepted as well, but without anything but literary evidence — has been systematic denial (or, to expropriate a phrase, denialism) and denigration of the idea, not only of Vikings, but any other contact of any kind.
Antiquity of humans in the Americas was held to be perhaps 3000 years, and nothing found could be considered older, and anything obviously older was rejected as a blunder, misinterpretation, or outright hoax. That had nothing to do with transoceanic contact, but had a common root in an isolationist ideology, nothing more.
Dendrochronology antedates radiocarbon dating, and involved matching up the sizes of tree rings (a climate-based approach I suppose) obtained from timbers used in, for example Four Corners area construction. Unrelated to that, Clovis finds were being estimated at much greater ages, and those ages were being resisted as far too high and unsubstantiated.
Once RC dating started, the antiquity of Clovis finds was no longer in doubt (or rather, not much longer, as the older gen croaked out). Instead of opening up inquiry, the Clovis date became the new glass floor beneath which nothing can ever be found. That Clovis-first-and-only generation is dying off, but as we can see with that new find of a 12K old skeleton in Mexico, is not quite dead.