From what I recall of the article in National Geographic a while back, they've loads of archaeological evidence from Greenland, and it was not just the climate which did them in, but the Reformation. Things got very nasty in Iceland at about the same time, with the Lutherans imposing death sentences for things which had not been punished before - similarly, Sami shamanic practices were attacked in Finnmark. It seems that in Greenland, the Norse decided that they could not borrow ideas from the Inuit which might have kept them alive, because they were associated with paganism. As if furry skin coats and trousers were the work of the devil.

The last records of travel to and from Greenland were contemporaneous, as I understood it when I read it. And the Norway end decided not to continue the trade journeys. Nice.

I don't know if any work has been done on the genetics of current Greenlanders to see if there were any survivors.