Marvel has recently confirmed that their Comic-Con slate will be including both Captain America: The Winter Soldier and Thor: The Dark World, and has also dropped hints to Phase 3 of their movie universe. According to the official press notes, the Marvel panel will include “an inside look at the ever-expanding Marvel cinematic universe.
It’s very vague, but considering the significance of the Comic Con (and the fact that Marvel is still essentially one of the most relevant companies in the comic book industry), the timing is very right for the big reveal for their Phase 3 lineup, which are all untitled at this point, with the possible exception of Ant Man, which is penciled in for November 6, 2015.
Don’t forget that Marvel has also previously used the convention for huge announcements, including the Avengers thingie back in 2010, so we’re keeping our fingers crossed. It’s a done deal anyway, even if there’s no announcement about Phase 3, their other stuff should be huge enough to warrant a Comic-Con announcement.