That seems like a serious extension of her powers as they've been portrayed in the comics.
I mean, it's movies so you can hand wave what you want. They lived in hiding, etc. It just feels like putting the X-Men in is a big lift, and the X-Men mythos are already so convoluted they may be best off as an alternate universe. F4 is much narrower, but their villains ****ing rule and are capable of being universe-level threats, so I would prefer them.
Dr. Doom, Annihilus, Galactus, Kane the Conqueror... just so good. After Magneto and Apocalypse, you either have to get weird with the Phoenix Force (plus side you can draw in the Shi'ar, downside you *really* have to commit to build that up), or you have lame-os like Mr. Sinister.