"X-Men: First Class" director Matthew Vaughn has opted out of directing that film's upcoming sequel "X-Men: Days Of Future Past" at 20th Century Fox reports Deadline. The real surprise though is that the name at the top of the studio’s replacement short list is Bryan Singer, the filmmaker who launched the "X-Men" cinematic franchise in the first place. Singer penned the treatment and produced 'First Class' which was directed by Vaughn.