I think you're right. Nate Grey is the only mutant besides Legion with that kind of power. We've seen in teasers that he's likely to get involved somehow. And if the first issue is any indication, mutants are going to have a huge existential crisis on their hands. If they now live in a world where they're destined to just fade, then why stick around? Nate Grey may help give them an out. I just hope it's not too similar to House of M or Age of Apocalypse. I think for a story like this, a little nuance will go a long way.