I've said before I think they should take a page from the Ultimate U and make Carol Danvers Fury's XO. Then she can get a sizeable role in the S.H.I.E.L.D. film Jackson is signed up for, possibly wind up empowered by the end of it.
Otherwise, perhaps Sharon Carter? If this is the film where Cap wakes up, she could have a small role as an attaché or something of the sort, which then becomes an important role in the next modern-era Captain American film.
Hmm, Maria Hill?
Fictitiously yours, Trent Roman