So I don't think M-Pox was made to kill the x-men. I think it was just another part of marvel's plan to rebrand the x-men as another franchise they actually own. We've seen more and more x-men join the Avengers and Inhuman teams and now mutants are dying from m-pox and there are no more new mutants being born.
I think what will happen is the "cure" to the m-pox will be that they will do something that alters the genetics of mutants and it ends up turning them into inhumanes.
You might not agree or like it(I don't like it either) but I just wanted to call it because im so sure marvel is gonna do it. >:D