Before development and filming of the Avengers 2012 movie, Morena Baccarin addressed to the rumor of her portraying the Wasp and contacted Joss Wheaton that she would definately do the part. Too bad they didn't. But with a second phase of Marvel movies coming to theaters soon and a third phase announced, there is still a chance for Morena Baccarin to be casted as Janet van Dyne, afterall she did respond to the rumors and appeared in one of Joss Wheaton's previous films called Serenity and with Olivia Munn ending up casted as a news reporter in Iron Man 2, Baccarin is very much likely the front runner for the role as Wasp in any of the next upcoming films, especially Edgar Wright's Ant Man.
Now if some of you are thinking that actresses like Rachel McAdams would be casted because of the Ant Man filming taking place in England, Mila Kunis for being short with brown hair like the character, or Olivia Wilde for having to resemble on of Janet's comic versions as the character Quorra from Tron Legacy, you may want to think back to some of the characters from the previous films and notice how some of them do not look exactly like they do from the comics or the shows. For example, Abomination appeared in The Incredible Hulk with golden brown skin instead of green and his ears were normal instead of scaly. The Frost Giants from Thor not being as giant as they usually look. And let's not forget that The Mandarin in Iron Man 3 is not Chinese but afghanistanian. So just to let you know, characters in the movie are not always gonna look exactly like they do in the comics by looks and especially by height. Plus with more actors coming into the franchise, Marvel is surely not going to cast too many expensive actors for the roles.
Morena Baccarin hasn't done much major film roles so for the record, she is most likely to be the one casted as Janet van Dyne/The Wasp for the future movies of the Marvel Cinematic Universe so to be sure, stay tuned