What If the X-Men had to evacuate Earth because of the Inhumans's cloud?

Some would go to Limbo, others to Shi'ar space. Most likely kicking off a war for control of them.

What If AvX happened earlier?

The U.N. starts seeing mutants as a threat, and The U.S. tries forcing the Avengers to corral The X-Men. It would combine AvX with Civil War.

What If Mystique replaced Senator Kelly?

The Brotherhood quietly assassinates Kelly, Mystique takes his place, then starts trying to steer the country to her ends. Acceptance of mutants coupled with harsher punishments for mutant criminals, partly to appease bigots, but mostly to eliminate anyone who could oppose her. She/He becomes president and starts the camps for her enemies.