The latest genetic studies show that the human race was down to about 5 breeding females at one point. If we could make it through that sort of near-extinction, just about anything could.
A geneticist with a british accent said so on PBS (Nova no less) so it must be true.
I suspect that if sasquach is real there is enough desolate woodland in North America to hold at least a few dozen of them even if they each require a huge territory.
Nice story by the way, PBP.