Originally Posted by Nell2ThaIzzay
If they HAVE to make an X-Men 4, and in the process they HAVE to bring back the characters who met certain fates in X-Men: The Last Stand, here's how I would personally do it:
-Xavier, Cyclops trapped in Astral Plane
Jean's powers trapped the minds of those she "killed" in the Astral Plane. From here, I would go with a story arc similar to that of X-Men Legends, and I would have Moira, on Muir Island, with the help of Forge, create a portal that would allow the X-Men to go into the Astral Plane to rescue Xavier and Cyclops. Moira would be involved with this because of Xavier trying to contact her through the brain dead patient. However, he wouldn't fully be able to return from the Astral Plane, and thus, Moira and Forge work on a portal to the Astral Plane, and the X-Men go into the Astral Plane to rescue Xavier and Cyclops. This arc leads for a potential Shadow King confrontation, as well as potential returns of Banshee (even as a cameo) and Emma Frost, depending on what story arc you want to take.
-Magneto is too powerful for the cure
X-Men: The Last Stand introduced the movie universe to the concept of mutant "classes". Magneto is established to be a Class 4 (Callisto: "There are 87 mutants in here, and none of them are above a Class 3, other than you two"; Xavier: "Jean is the only Class 5 mutant I've ever encountered"). I think that it would be pretty realistic to assume that Leech was not a Class 4 mutant. Therefore, my theory is that Magneto is able to regain his powers because the cure, extracted from Leech's DNA, was not powerful enough to permanently cure someone as powerful as Magneto. However, Rogue and Mystique could be established as Class 3 mutants, weak enough for the cure to be permanent.
That would actually make sense about the cure. Personally for an X4 I don't really want to see Magneto (even though I love both Fassbender's and McKellens Mags, I really want some new villains) But that could be a way of bringing him back later. Even though neither he nor patrick stewart are getting any younger.
The Astral Plane would be trippy and out there, but I think this is a much better way of bringing back those characters than cloning or whatever, or by expecting us to believe that Cyclops was just knocked out the whole movie. They could even have Jean's consciousness in there to help give proper closure to her and Scott's relationship.
If they make both movies they could even work on a way of Emma Frost helping to get Charles back. Setting her up in a First Class sequel to become an X-woman or ally eventually.
I never liked any of peoples reasons for the cure not working/resurrecting dead characters, mainly because I thought it would cheapen the Last Stand even more.
But both of these ideas/explanations are not half bad.