The boring answer is — no one knows (as for the potential reinvasion). Rationally Putin has already lost too much on the war that, by his estimation, should’ve lasted a week at the most… but he’s already all-in, rebuilding the entire country in the image of that war, making it the main ideological basis of putinism, it’s hard to undo it. And rational assessments of Putin never work anyway.
As for NATO — assuming that Trump is going to push for negotiations, leaving Ukraine in a position of significant disadvantage, I’d assume that them not joining NATO (at least for some time) would be one of the first points of the deal…
Maybe Trump does something unexpected and, you know, doesn’t throw Ukraine under the bus but I find it unlikely