I mean, they have to come up with something to spread out the actors to keep them around. I imagine Avengers 3 will be the fallout of Civil War introduced in Cap 3, and the team will get back together in Avengers 4 before focusing on newer characters that they are certainly going to introduce in Phases III and IV.

Keep in mind, there are also the Netflix Defenders characters (Daredevil, Jessica Jones, Luke Cage, Iron Fist) coming too.

I am willing to bet Spider-Man pops up in a film sooner rather than later.

FF looks to be on the fast track to be highly disappointing, so who knows what will happen there too.