In an interview with Vanity Fair, it seems Scarlett Johansson (who plays Black Widow in the Marvel films) has confirmed that Brie Larson (who has been cast to play Carol Danvers, a.k.a. Captain Marvel) will indeed appear in AVENGERS 4 (a few months after her own solo film). Here's the quote:
It’s bittersweet to imagine not having these films to come back to. I’ve been living this story with these people for 10 years through ups and downs. We’ve built a great family. Personally, it feels like a loss. There’s a gain that comes with that for each one of us. We have Brie Larson on this film. She’s here before shooting the stand-alone Captain Marvel movie so we get to watch her get her feet wet for real. She’s so great, but a really cute thing happened the other day where Hulk is standing next to her and Joe Russo told her to put her hand in front of Mark [Ruffalo]’s face to stop him, and she’s like, “In front of his face?” And they explained, “that’s where his chest is,” and she looks up and yells, “I’m new! I’m new!” I’m like, “damn, girl.” It’s very surreal for me to watch these new cast members come in and get their feet wet and breath new life into these characters who are so iconic. I feel a lot of joy for the next generation. It’s a bittersweet feeling but overall it’s a positive one. I feel good about the work we’ve done and the work I’ve done.
Giving further credence to her inclusion, is this tweet, showcasing all the badass Marvel ladies (including Larson):
So that's exciting! It's a shame we couldn't have seen Captain Marvel sooner, but at this point it'd probably make INFINITY WARS more overstuffed than it already is – and at least she'll have a solo film before her AVENGERS appearance. Let's hope they stick the landing (pilot pun)!
In the meantime, AVENGERS: INFINITY WAR hits theaters May 4th, 2018.