We’ve learned from Deadline that Matthew Vaughn has decided that he doesn’t want to direct X-MEN: DAYS OF FUTURE PAST, the sequel to X-MEN: FIRST CLASS. There is no explanation out there right now as to why he bailed, so I usually just assume its money related.
So the studio is left without a director, which sucks for them. The thinking right now is that Bryan Singer will step-in and take over the directing duties, but nothing is set in stone.
Singer would be the logical choice to take over this movie since he has a history with these characters, so I say go for it. Seems like a good match.