Re: your first point, no, because they never retroactively undo the past.
Re: NIL payments, I don't think so, if the kids are just betting on their own. But I think the NIL play is that ESPN Bet, Draft Kings, etc., could use the kids as spokespersons, which would involve allowing them to bet and perhaps show via content creation how much their winnings are. And yes, for DII and DIII kids that could be huge. Olympic sports too.
I'm just trying to figure out the motivation here. It's the attorney in me. The NCAA isn't just doing this for fun. Someone is getting something out of it.