With the modest commercial and major critical success of X-Men: First Class a sequel was inevitable. If certain sources are to be believed the sequel could be a trip to Days of Future Past. A trip to an alternative future where mutants are ruled by Sentinels would be a smart move by 20th Century Fox.
Days of Future Past was a two part story running in X-Men #141-142 written by Chris Claremont with art by John Byrne. In it we are shown a possible future where mutants have been rounded up into camps and everything is ruled by robotic Sentinels. Rachel Summers and an adult Kitty Pryde send her consciousness back to her younger self to warn the X-Men in an attempt to change the future.
This isn’t the first time Days of Future Past was the basis for another an mutant related endeavour. The one and only season of Wolverine and the X-Men, which than hinted at an Age of Apocalypse second season.
Doing a film based on Days of Future Past would be fun. Visually you get to go through a robot filled wasteland. With this being an alternate future you can also play with expectations of certain characters.
X-Men: First Class was inspired by James Bond films. Why can’t this movie also draw from other films, in particular The Terminator franchise. Now, yes The Terminator series hasn’t aged well beyond Judgement Day. If you're going to do a movie where robots rule the future and you go back in time to try and change it The Terminator is bound to come up fairly or unfairly. It also would be smart to draw on the lone season of Wolverine and The X-Men.
In Days of Future Past Kitty Pryde has Rachel Summers send her consciousness back to her younger self. That is just a bit to comic booky even for me. Instead turn Kitty Pryde into a Kyle Reese type character. Split the film into two eras Rachel Summers in the bleak future and Pryde in the past trying to overt it, which is what went down in Wolverine and the X-Men,Splitting the movie into two sections would let them play with (and license) more mutants. Pryde would be sent back stop is the assassination of Senator Robert Kelly which starts mutant Judgement Day.