As much as I would love to see Ms. Marvel in this movie, I would be very disappointed if she was only added because people complained about gender imbalance. Put her in the movie because she's a cool character, not to fill a quota. Keep your affirmative action out of my movies!
What, you don't think it's important to argue for representation in the media?
I'm not expecting to see much more in the way of team-members, though; the cast is pretty big as it stands, and then you need villain(s), etc.
Mockingbird would probably be the easiest of the notable recent female Avengers to introduce, since, like Hawkeye (the only notable new addition in the film itself, from the looks of it), she can be explained in about ten seconds. Wasp doesn't make sense without Ant-Man, and we know he's not in it; She-Hulk and Ms. Marvel likewise have origins that would require a decent bit of time to explain properly; if they even have access to Scarlet Witch, they certainly don't to her backstory.