This initial post-Mutant Massacre arc sees two future dystopias. The first, in New Mutants #48, is your Days of Future Past timeline (apparently different enough that it's reckoned to be a different version, but I don't see that myself), and the origin of that is explained. But the grimness of that future as Uncanny had it cannot withstand the optimism and wish-fulfilment of New Mutants and we soon discover that in addition to the few surviving New Mutants (Dani and Sam), Lila Cheney is alive and has helped them set up a colony on her Dyson Sphere.
In #49's future dystopia, what was left of the X-Men, led by Magneto, have allied with the Hellfire Club to take over the world. New York has become a dystopia in part modelled on 2000AD's Judge Dredd: complete with Arbitrators (not Judges) with eye-obscuring visors. The more sinister part is their resemblance to the New Mutants uniforms, and the revelation of Bobby and Amara's leadership role in this regime. Our kids are helped by an elderly Kate Power, who clings to the ideals of the past.
Both groups are rescued by Magik, who brings ideal help for dealing with the future in the form of their mentor: Professor Xavier. He's been worried about what Magneto might be getting up to in his absence (having nightmares about the Holocaust and joining the Lords Cardinal of the Hellfire Club would seem to be the order of the day), and he's happy to, with Binary, join Illyana in a rescue mission.
Another father figure is part of the story, of course: Magus, who they had gone into Limbo to escape. Thanks to the power of teamwork (and Xavier and Binary, and willing self-sacrifice from Cypher and Warlock), the Magus is regressed to a state of infancy. Will he grow up better this time? Or will someone pretending to be Eric the Red age him back to distract them, as when the same trick was played on a character with one more 'n'. At the end it looks a lot like Xavier is going to return to Earth and stay... I'd wondered how long that would last: this is shorter than I was expecting.