You can have a fission in their love story to keep it interesting. With Cyke blaming something like Xavier's death on Jean or someone else on the X-Men, and then forming an offshoot of the X-Men that does the dirty work. Maybe Cable is introduced as a time traveller just to give the team a veteran presence.
While I don't think they are taking the important arcs from AoA here per say, it was definitely a fitting option. But honestly, I don't see a McAvoy led team getting another trilogy, as much as I like where he has taken the character. This honestly could be a one shot movie and these characters don't appear for some time.
I just would have closed the books on Magneto and Xavier here. There is only so much more you can do with them. If they end up friends at the end of this, then that removes a lot of the 40 plus years of drama between them.
I'm pretty confident in saying the next major ensemble will involve Cable as a time traveler interacting with these mutants, at least some time within the next trilogy. So any direction is possible.