Re: X-MEN 4 release?
Clearly the studio didn't intend an X4, or X3 wouldn't have tried to close off so many storylines and reach a conclusion.
After the production nightmare of X3 - large cast, huge salary bill, contractual headaches, Singer leaving, Marsden leaving, Vaughn leaving, Rousselot leaving, Ratner signing on with eight weeks before filming started - i wouldn't imagine Fox is overly eager to do an X4.
I'd written a story for an X4 that developed and continued the ideas in X3, including bringing in Gambit and some other new characters, but with Gambit set to be in the Wolverine movie, it looks like they are going down a different road.
It's likely that the Magneto movie will become a restart such as X-Men Origins, partly because Magneto's past is probably not seen as enough to create a blockbuster.