Seems there may have been a good reason for Matthew Vaughn bowing out of directing the sequel to X-Men: First Class, X-Men: Days of Future Past.
Namely, Star Wars.
The Collider has it that Matthew Vaughn is in talks to direct the next Star Wars movie, which Disney set for a 2015 release following their announcement of the acquisition of Lucasfilm from George Lucas for $4.05 billion. It's stated that Star Wars was the reason for Vaughn dropping out of the X-Men movie.
Vaughn previously wrote and directed X-Men First Class as well as wrote Kick-Ass, The Debt and Stardust.
Regarding X-Men: Days of Future Past, it's been said that Matthew Vaughn may stay on as producer. Bryan Singer was recently announced to be the new director.
No details are known about Star Wars Episode VII, but it has been said to be an all-new original story and both Mark Hamill and Carrie Fisher have previously talked with George Lucas about it, as well as, reportedly, high profile Hollywood screenwriters.
For more on Star Wars, head on over to the Cosmic Book News Star Wars Movie Hub.