Well one can assume it's all happening because Wolverine took all the "good" X-Men with him to form the Jean Grey Institute for Higher Learning back in New York, and right now Cyclops is acting like a goddamn dictator and assembled all the most powerful mutants he had left (Including Emma Frost, Storm, Magneto, etc) and put them on a team he literally calls his "Extinction Team"
all the civilians living in cali are terrified and apparently Magneto just slaughtered a bunch of protesters so I guess Cap will get fed up and decide to kick their asses. Not sure why Wolverine would want to get involved now that he has his new school. Iceman is like third in charge there.
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~Zen