Hmmm. I understand why they're saying that was the last of the series (but that they may do spin-offs). There were quite a few 'named mutants' they got rid of, one way or another. Rogue, Prof Xavier, Magneto, Mystique, Jean Grey, Scott, though perhaps, just perhaps, they aren't all gone.
- Scott - we didn't see him go.
- Xavier - well, he's been reincarnated (you did see the post-credits scene?)
- Magneto - he's still alive, just stripped of his powers. Yet, we see him just able to influence a chess piece, so perhaps the 'cure' isn't permanent.
- Mystique - again, she's just been stripped of her powers.
- Rogue - ditto.
- Jean Grey - well, OK, she's dead. Again.