User blog comment:KillRoy231/Days of Future Past questions and review/@comment-4410723-20140526235356

Here's my logic: Timeline A: First Class accurate; Trask is not any kind of threat; Mystique is free; the first three movies happen. Timeline B: First Class accurate; Trask shot by Mystique; Mystique captured and presumably killed; Sentinels produced; Beast killed in 2015; extinction imminent. Timeline C: First Class accurate; Trask saved and Raven wounded; Sentinels hacked by Magneto; Wolverine badly wounded, Mystique threatens Nixon; mutants are hailed as good people and the world is saved; everyone is alive.

As of now, the movies now run off of Timeline C, negating the need for any heavier explanation, really.