According to Kevin Feige seaking to MTV...
"'Ant-Man' is definitely part of Phase Three," Marvel's Kevin Feige told MTV News during our recent interview. "Like 'Iron Man 3,' it's certainly set in the Marvel Universe, but it's also through the lens of Edgar Wright — which is the only reason we're making the movie."
"I've known Edgar since our first lunch together at Comic-Con in 2004," he continued. "He asked me what Marvel was doing with 'Ant-Man' — we weren't even a studio then; what a difference eight years makes! It's very much an 'Ant-Man' origin movie from the perspective of Edgar Wright and his co-writer Joe Cornish. It will of course be firmly planted in the MCU, but a different corner than we've seen before."
"Beyond that… 'Ant-Man' is the only one officially announced, but you probably don't have to look too far to guess at the next list of characters we're toying with and beginning to develop."
Could the oft-rumored "Doctor Strange" be a part of those plans?
"'Doctor Strange,' which I've been talking about for years, is definitely one of them," he confirmed. "He's a great, original character, and he checks the box off this criteria that I have: he's totally different from anything else we have, just like 'Guardians of the Galaxy.' He's totally different from anything we've done before, as is 'Ant-Man,' which keeps us excited."