The whole thing was setup to be undone by Moira's lives resetting on her death.How is there no going back? All they have to do is blow up the planet and we're back to before X of Swords, there's a reason only Arakko was plopped on Mars, they're leaving the door wide open to undo this in the future.
When they want to move on without all of the hardcore stuff of this run, they can kill Moira, which will reset time back to her birth. Then they'll keep all of the Marvel canon up to the point where they want to reset, with the difference being that Xavier, Moira, and Magneto did things differently so mutants end up not colonizing the moon in such a spectacular fashion, Arakki mutants are trimmed down except for the ones that matter like Isca, and any other plot point that contributes to the eventual mutants vs machines vs universal black hole intelligence.