Wasp almost made into Captain America: Civil War.
The writers on Civil War, Christopher Markus and Marcus McFeely, filled in the Collider that if Wasp had made it into the Ant-Man movie, Wasp would have been in Captain America 3.
CHRISTOPHER MARKUS: You know, almost everybody made it in. There was a period where we talked about bringing Wasp in. There was actually a draft Wasp was in because she was so almost on the edge of being in Ant-Man, but then you’re taking something awesome out of the Ant-Man team’s quiver if it’s like, “Well, we’re doing her!” Plus she had a similar skill set, so it’s like “Well, maybe we just isolate it to Scott.
MARCUS MCFEELY: When you see the movie, you see that Scott is his own comic relief so it would change that a little bit. They would be this pair. Everybody else we would talk about them and then they’d go away, but we got most everybody back.
Nine months ago also saw Kevin Feige address why they didn't use Wasp in Captain America: Civil War.
She was included in early versions of [Captain America: Civil War] but there are so many characters in Civil War that we didn’t want to do her a disservice, like she flies in, ‘I’ve got the costume now’, and she flies out.
With Ant-Man, and I’m not saying thats what Ant-Man does in the movie, but we already know him, we’ve already seen him. We haven’t seen her as Wasp and we don’t want to rob the opportunity of seeing her in the outfit for at least almost the first time, and seeing her dynamic with Scott in a way it could play out, so we’re saving it. But its going to be in Phase three for sure."
While Wasp didn't make it into Captain America: Civil War, Evangeline Lilly will suit up with Paul Rudd in the sequel to Ant-Man, aptly titled Ant-Man & Wasp, which hits July 6, 2018. It's also possible we could see Wasp in Avengers: Infinity War prior to that on May 4, 2018.
"Captain America: Civil War" has a May 6, 2016 release date directed by Anthony and Joe Russo starring Chris Evans, Robert Downey Jr., Scarlett Johansson, Jeremy Renner, Elizabeth Olsen, Sebastian Stan, Anthony Mackie, Frank Grillo, Paul Bettany, Don Cheadle, Emily VanCamp, William Hurt, Martin Freeman and Chadwick Boseman as Black Panther.
Captain America: Civil War picks up where Avengers: Age of Ultron left off, as Steve Rogers leads the new team of Avengers in their continued efforts to safeguard humanity. After another international incident involving the Avengers results in collateral damage, political pressure mounts to install a system of accountability and a governing body to determine when to enlist the services of the team. The new status quo fractures the Avengers while they try to protect the world from a new and nefarious villain.