Marvel Studios originally had plans to conclude "Phase 1" of its shared cinematic universe by releasing The Avengers and then begin "Phase 2" with Runaways later in summer 2012, but the latter project ended up being put into turnaround; as it were, Runaways writer Drew Pearce went on to co-pen the actual beginning starting installment for "Phase 2," Iron Man 3 (not to mention maintain a heathy working relationship with Marvel). However, history won't repeat itself in "Phase 2," as the 2015 sequel Avengers: Age of Ultron will be joined by Edgar Wright's long-developing Ant-Man (kicking off "Phase 3") later that same year.
Wright's superhero movie was previously scheduled to arrive in November 2015; that is, almost exactly two years after Thor: The Dark World's theater premiere date (the Fall season is untested waters for both Marvel movies and comic book genre blockbusters in general). However, two months back, Sony decided to claim Ant-Man's Fall date for the 24th James Bond film, and since then we've been anticipating that Marvel would be reshuffling its "Phase 3" beginning installment to another (Fri)day (rather than force Hank Pym to square off against Agent 007).
Ant-Man is now slated to open in theaters on July 31st, 2015, just a week over three months earlier than its previously-set November 6th date that year. Several heavyweight blockbusters and tentpole sequels - Avengers: Age of Ultron, Terminator 5, Pirates of the Caribbean: Dead Men Tell No Tales - will have opened in theaters and finished the most lucrative portion of their theatrical run by that point; though, director Zack Snyder's Man of Steel sequel (rumored to be titled Batman vs. Superman/Superman vs. Batman) will have arrived on the scene two weeks before Wright's film is unleashed. As it stands, though, the sole opening weekend competition for Ant-Man is going to be Miss Peregrine's Home for Peculiars, which is based on Ransom Rigg's popular novel.
So far, details are by and large being kept under wraps on Wright's Ant-Man script, which was co-written by Attack the Block writer/director Joe Cornish (Wright and Cornish also co-wrote Adventures of Tintin with Steven Moffat). What little information has been confirmed involves what not to expect from the film; namely, the megalomaniacal robot Ultron, who is the creation of Hank Pym in the traditional Ant-Man comic book mythos but in the MCU continuity will get a new origin story (and instead serve as the antagonist in writer-director Joss Whedon's Avengers movie sequel).
Ant-Man is expected to uphold the precedent established by "Phase 2," where each installment gets its distinct shape thanks to the director in charge (Iron Man 3, for example, is foremost a Shane Black movie). Therefore, if you're been a fan of Wright's past work - Shaun of the Dead, Hot Fuzz, Scott Pilgrim vs. the World and The World's End - and want to see a superhero movie in that style, then Ant-Man is probably among your most (if not the most) anticipated Marvel projects on the horizon... despite the lack of concrete details or casting so far.
Ant-Man is now scheduled to open in theaters on July 31st, 2015.
Source: Marvel Studios