Just when you think Marvel Studios can't top themselves is when they do just that. During their Marvel Event in L.A., they announced that instead of having a single Avengers 3 movie, it'll be a 2-part movie event called Avengers: Infinity War. (It's okay to make a mess in your pants. It's natural when you read that.)
Anyway, Avengers: Infinity War, Part I comes out out on May 4, 2018 and Avengers: Infinity War, Part II comes out on May 3, 2019.
How this will work with actor contracts for Robert Downey Jr., Chris Evans and Chris Hemsworth remains to be seen because they were only contracted for a singular Avengers film. Maybe having a 2-parter is a contractual loophole to get them into Part I and II. As of now, this is unknown.
Oh... and Marvel revealed this teaser image of Thanos for Avengers: Infinity War, Part I & II.
Related Posts: Marvel Studios Reveals PHASE 3 Which Includes New Franchises: DOCTOR STRANGE, BLACK PANTHER, CAPTAIN MARVEL & INHUMANS
Chadwick Boseman Confirmed as BLACK PANTHER & Will be Introduced in CAPTAIN AMERICA: CIVIL WAR; Plus Concept Art