What happened at the end of Days of Future Past?

What happened at the end of Days of Future Past? Mystique decides to walk away, essentially leaving the entire world to think they just saw the president saved by a mutant. This leads to the dismantling of the Sentinel program, undoing the bleak future.

Mystique decides to walk away, essentially leaving the entire world to think they just saw the president saved by a mutant. This leads to the dismantling of the Sentinel program, undoing the bleak future.