In comics, there were very few of the main mutants who got snapped:
Angel
Beast
Firestar
Iceman
Jean, I think.
You'd think there were much more, isn't?
I liked the idea of bringing mutants back after the snap, but it makes no sense because nothing Hulk did would indicate this was something that happened. And the mutants just becoming mutants in adulthood doesn't have the same weight as the "born this way" canon. Are you telling me that Magneto and Xavier JUST became mutants at 40? Magneto doesn't really hold much as a human hater if he hadn't been developing that sense of superiority for decades.
Putting aside that I'm sure they are gonna fuck up their stories and casting, I am not looking forward how they are gonna even explain them. They waited too much for them.