What else are we going to learn by the time the film is released? Probably a lot, since there is almost a full year until it arrives, and we will likely keep getting various releases of information in the meantime. Fans have been keeping an eye on the development of the production on all fronts, so Marvel can’t really hide what they’re doing right now.
It’s safe to say that if anything interesting starts developing behind the scenes, it won’t be long before fans start spreading the news all over the Web. Various members of the press have been eager to learn something about the upcoming film as well.
So, at this point, Mavel just have to say the word and they will immediately enjoy lots of hype for their announcement. The studio probably realizes this too, and that could be the reason why they have been keeping relatively quiet, as they want to make sure that any official announcements they make are as perfect as possible.