At an event in Los Angeles today, Marvel Studios confirmed that the third Captain America solo film, set for release on May 6, 2016, will be titled Captain America: Civil War.
The story has been reported to center around Marvel's Civil War storyline, which saw heroes at odds both philosophically and later physically over a proposed Superhero Registration Act. The two factions in the comics were led by Captain America and Iron Man, and Robert Downey, Jr. will play Tony Stark, the film's primary antagonist.
It's been widely rumored that the Avengers lineup will be significantly shaken up by the events of Avengers: Age of Ultron, a clip from which will debut on Marvel's Agents of S.H.I.E.L.D. tonight.