A while back there were rumors that the lineup of the Avengers would be changed by the end of the upcoming Age of Ultron. If for no other reason than the expiring of certain contracts would dictate a need to change the roster. Then came rumors of a Civil War story being in Avengers 3, which would guarantee a different roster of Avengers. But again, there was no confirmation.
If Buzzfeed is to be believed though, it’s going to happen one way or the other.
Kevin Fiege states that, “The Avengers films, ideally, in the grand plan are always big, giant linchpins,” says Feige. “It’s like as it was in publishing, when each of the characters would go on their own adventures and then occasionally team up for a big, 12-issue mega-event. Then they would go back into their own comics, and be changed from whatever that event was. I envision the same thing occurring after this movie, because the [Avengers] roster is altered by the finale of this film.”
So the big question would be, “who’s replacing who?” We know that Scarlet Witch and Quicksilver will be on the team, and that possibly Ant-Man (Scott Lang) and Doctor Strange could be in line to be in the movies. But will that be all? Time will tell I guess…