Dofi, good questions – the population in eretz yisroel is under no obligation to leave, because the individuals aren’t violating the oaths by living there. They don’t have to to anywhere. But they should dismantle the state and accept being a state of the US or whatever.
Also, while it “could” have been permanent, it was never intended to be; i believe the gaon writes that. Same way chizkiyahu was fit to be moshiach, but it clearly was not the Divine plan.