Disney has put up the money to secure a couple of spots during the big show and there is only a few things they can put into place there to get the fans talking. Captain America: Civil War is expected to be one of them. Marvel has a crossover promotion with Coca-Cola so that might play into the commercial spots as well.
There is one character that viewers will not see in Captain America: Civil War. According to Mark Ruffalo, he was supposed to be in Civil War, but was cut out of the movie. The reason was that at the end of Age of Ultron, the Hulk moves on and Marvel does not want to reveal where the Hulk is and why since he there.
So it looks like Captain America and Iron Man are certainly going to be a part of the new movie. Of course, we are also going to see Black Widow, Falcon, Agent 13, war Machine and Hawkeye just to name a few.