In a release schedule update sent to press, Disney revealed dates for two as-yet untitled Marvel Studios films: May 6, 2016; and May 5, 2017.
That's also effectively all the information the public has at this point about these relatively far-away movies: The release states, "We look forward to announcing more details about these films as well as the sequel to The Avengers (opening 5/1/15) at a later date." So, the big questions — like which characters will be featured in these two films — will be left to speculation for now.
The news shows that Disney and Marvel are clearly keen on staying a dominant force on the first weekend of May, where Iron Man 3 launched this year, and Avengers debuted the year before — both went on to make more than a billion worldwide. Next summer, though, that spot belongs to The Amazing Spider-Man 2, which, while based on a Marvel character, is a Sony picture due to a long-standing licensing deal.
Iron Man and Iron Man 2 opened on the first weekend of May in 2008 and 2010, respectively, as was fellow Marvel Studios production Thor, in 2011. The first weekend of May in 2009 saw the release of another movie based on a Marvel character, X-Men Origins: Wolverine, part of Fox's long-term licensing deal.