From Entertainment Weekly‘s new Iron Man 3 cover story,
A source confirms to EW that the twin characters Quicksilver and Scarlet Witch will be joining The Avengers 2, which Whedon hinted at recently when he said he was writing a brother-sister duo into the movie. Feige maintains a poker face on that scoop, saying only: “I’m not confirming or denying. The draft could change six months from now.”
Look, I know a lot of people hate the Fox Marvel Movies, and no one is denying they have a couple misses, but I happen to have liked the X-Men and Fantastic Four movies. And, I can see no way that this will work unless they merge the Universes. So, this means there is a fifty/fifty chance of Fox/Marvel/Disney working together.
In other news, we all still hate Sony, and Sony still hates us.