Even if so, those generations provide time for the cultural intermixing I mentioned to occur.
Very minor and virtually unnoticeable in the long term, not "Beothuk vocabulary, architectural practices, hunting practices, and yes, mythology" in a major way.
There are also countless examples where even iron working societies do no such thing. Much of Zomia, for instance, was in direct contact with iron working societies but has had a hunter-gatherer mode of production for quite a long time.
Funny how you mention Zomia considering the original inhabitans, the Hoabinhians, have been mostly(completely? Outside the Onge-Jarawa) replaced in the region, any small hunter-gatherer population is mostly of recent Austro-Asiatic farmer ancestry and all spoke at the very least Austro-Asiatic, originating from the first major linguistic expansion we know of(which were later supplanted by Burmese, Thai, Austronesians).
Hell, there are a bunch of examples where that happened in the USA, and creolized groups resulted (for instance, some of the Métis trace ancestry from hunter-gatherer populations of the Cree).
The Metis formed small communities by virtue small bands of male traders, the Norse here wouldn't come as a male only population(they had a self-sustaining population in Greenland afterall)
You're trying to present as an inevitability something we know was due to contingent circumstances. The question we should be asking is, "What were those contingent circumstances, and can we duplicate them here?"
You are missing the forest while looking only for the trees that are convenient to your argument.
It doesn't matter how many small exceptions you bring from places that were already extremely convenient to lingering hunter-gathers(tropical regions) or single case-examples of creolization, I can bring dozens of examples where hunter-gathers were simply steamrolled from just Neolithic Eurasia, places as far as Portugal, Ireland and Southern Scandinavia ended up having at most 25% HG ancestry accumulated all the way from the southern Balkans or Italy, which means that in each migration(Balkans-Italy, Italy->Southern France etc) a larger % of replacement happened.
Similar things happened with the Bell Beakers in the British Isles, 80-90% replacement and that was between agriculturalist/pastoralist populations, not involving HGs.
Not just blanketly dismissing the possibility because "Lol hunter gatherers always lose."
Well it's simply true, there is a reason why widespread language families are a thing, because populatiosn routinely(in the grand scheme of things) end up having certain advantages that allow them to either demographically or politically/socially dominate a larger region through relatively rapid expansions and the shift from hunter-gathering to agriculture is one of those, not every HGs is replaced to the same extent but the Beothuk are hardly a candidate for survival. The HGs of Newfoundland were extremely small, extremely isolated and are encountering populations deriving not a simple Neolithic society but from a iron age population that is already familiar with complex political systems, has a stronger religious identity(both Christian and pagan) and has a well developed agricultural/pastoral package.
Hunter-gatherers survive where agriculture and pastoralism can't thrive and Newfoundland while not being a paradise is still free real estate for farmers and pastoralists, simple as that.
There's also the minor matter that, depending on the circumstances of the Vinland settlement's origin (for instance, is it a trading post that is lost contact?), it may be disproportionately male, leading to high intermarriage rates.
Yes if you try to create a specific convenient timeline you can do such a thing but that's not really the point of a "surviving Vinland", even in Iceland where the locals have 30-40% Celtic/British ancestry(mostly female-mediated) there is hardly that much Celtic influence, not anymore than you would expect from mere contact and proximity(involving the founding stock population as well) regardless of what people claim nowadays based on recent genetic find(all of a sudden people realized that there might be Celtic influence when their DNA tests told them they were 1/3 Irish, convenient)