Marvel has plans through 2021

Kevin Feige, the president of Marvel Studios, made an announcement stating that Marvel has films planned from now until the year 2021. Yes, that is just shy of 10 years of plans. He also reminded everyone that the plans for 2015 that we know about now were in motion back in 2006.
The plans in question include expanding the Marvel Cinematic Universe to include more characters and story arcs. This is to prove to studios and audiences that they can be successful outside of the five Avengers characters. This will include the 2014 release of Guardians of the Galaxy and the 2015 release of Ant-Man. Further films that have dates for 2016 and 2017 announced but aren't titled yet will most likely be new characters as well, such as Doctor Strange and a rumored film for Black Panther. I would wager that animated films aren't out of the question either.

It is likely that the 2017 or a 2018 release date will be The Avengers 3, so I wouldn't rule out a third movie for either Thor or Captain America if not a standalone movie for The Hulk. However, none of that is confirmed and until we got confirmation on anything for Phase Three other than Ant-Man we can just have the fun of guessing for now.

The next film Marvel has lined up for us is Thor: The Dark World which hits theaters this November. In 2014 we will have Captain America: The Winter Soldier and Guardians of the Galaxy.