Director Matthew Vaughn has expressed an interest in opening his X-Men: First Class sequel with the Kennedy assassination, but now the plot thickens as new evidence suggests the film will follow a story arc from the comic books which concerned another assassination: that of Senator Robert Kelly.
Ain't It Cool News reported today that 20th Century Fox have secured Days of Future Past with the MPAA Title Registration Bureau, giving a good indication that the next X-Men film will be distributed under this name. The title matches a two-issue story from the original Uncanny X-Men comic book series that deals with the splitting of reality into multiple timelines, where Kelly's assassination leads to widespread anti-mutant hysteria and creates a dystopian future in which mutants are kept in internment camps.
Days of Future Past was published in 1981 and the plot alternates between the present-day of the eighties (nineteen years after the setting of X-Men: First Class) and the dystopian future. Worthy of note is that Kitty Pryde is a major player in the story, as her future self possesses her younger self in order to warn the other mutants of their impending doom. In the chronology of the X-Men films Kitty would still have quite a few years to go before even being born, so if Vaughn and co. are going to use the comic book story arc then Kitty will presumably be replaced by another character.
At a guess I'd say that the film will most likely be a liberal adaptation of the comics, with the Kennedy assassination replacing that of Kelly. There should also be a scene where Charles Xavier has to play matchmaker to his parents at the Enchantment Under the Sea dance…
Oh stop booing, you knew that joke was going to happen eventually.