The Inhumans are going to be the Inhumans, they’re not going to be X-Men II. And if the film rights to X-Men at some point return to Marvel (which seems so unlikely as to verge on impossible) then we won’t have any difficulty doing new movies and stuff with them–there are fifty years’ worth of stories with more being added every month.
So you’re asking me what we’ll do when your assumptions take place, which I can’t really answer–because they’re a bit off-base.