Rumors have been circulating saying how once Thor: The Dark World wraps its production in England, writer/director Edgar Wright will start his production on Ant-Man and his film could be released as early as being Marvel's third 2014 release with Captain America: The Winter Soldier and Guardians of the Galaxy that same year.
With zero certainty about Ant-Man's theatrical opening, we have to guess it will come out after The Avengers 2 and potentially as the start of Phase Three. This also allows writer/director Joss Whedon to tease audiences after The Avengers 2 as to who the villain of Phase Three and The Avengers 3 could be with Ultron—just like what he did with Thanos at the end of The Avengers.
This would successfully set up an Ant-Man movie which would follow The Avengers 2 either later in 2015 or maybe in May of 2016.
More stories on Ant-Man:
Fan Movie Art of Ant-Man and Ultron Standing Face-to-Face
Ant-Man News: Filming to Start Sooner For Possible 2014 Release
Ant-Man News: Details of Test Footage Shown at Comic Con and of His Suit Too