Woah. What if killing Nixon is what stops Trask's plans?
So Nixon is anti-mutant and wouldve signed for the sentinel program.
The original Xavier stops Magneto from killing him anyway because thats what he wouldve done.
Sentinels end up causing the dystopian future.
Wolverine goes back to convince Xavier to let Nixon die. "I DON'T WANT YOUR FUTURE."
*gasp* what a trip that would be.