In Marvel's past, specifically in Phase 2, it seems as if the studio would only be releasing sequels until they were completed with a franchise, and then move on to another one. Phase 1 introduced the most mainstream superheroes in order to light the way to the Avengers, while Phase 2 seemed to be nothing but sequel movies to the first phase, with the exception of Guardians of the Galaxy. Now, Marvel is realizing that these franchises can't go on forever, and they're eager to introduce many new projects in the upcoming Phase 3.
"[Guardians of the Galaxy] fulfilled our desire to do something different, to start producing, each year, a film that was the sequel to a pre-existing, successful franchise and do something new. We're doing that next year with Age of Ultron, with Ant-Man, and hope to maybe continue that model in the coming years."
So now it seems as if Marvel will be planning to do one previous franchise film, while also introducing a brand new film franchise each year. However, this pattern won't be followed EVERY year according to Feige, but it will be a basis for the future.
"I don't know that we'll keep to [that model] every year, but what we're doing this year and what we're doing next year is: existing franchise, new franchise, existing franchise, new franchise. So I think it would be fun to continue that sort of thing. I don't know that we will [do that] all the time, but as a general model, I think that would be fun."
Feige has also expressed the desire to do one 'ensemble film' and one 'solo film' a year, meaning that films such as the Inhumans, Guardians of the Galaxy 2, the Runaways, Power Pack, and the Avengers may be taking more precedence in the studio's future projects. Let us know which future franchise you would like to see most!