You’re talking about something that goes back decades at this point, so to answer your last question first, while it’s not impossible, I don’t think we’re going to see a big resurgence of the Mannites any time soon. As I recall, the Mannites were an idea that Bob Harras came up with while he was writing AVENGERS but didn’t get an opportunity to use there. But it seemed like one that would be a good fit for the world of X-MEN and give them the opposite number to mutants that at the time they were talking about wanting. But none of the writers who were working on the X-books at the time were the person that came up with the idea (and there was a bunch of creative turn-over during that time as well), so my guess is that it became an idea that nobody had particular ownership over, and so it just naturally fizzled out. But that’s my memory of a sequence of events from long ago that I was not directly involved in, so I could be wrong.