To be honest, I'm not really that interested in a Black Widow movie. I mean, I love Johanssen, but I think the character works much better in a supporting role and I hope we continue to get more exposition with her over time. The bits and pieces here and there actually add to the mystery of the character.
That being said, I'd love to see Marvel do a film with a female protagonist (or at least more than just Ms. Marvel). The problem is that there's not a lot of good characters to choose from that aren't licensed to Fox. I'd like to see Evangeline Lily be a break out character of Ant Man and become the Wasp -- I'd actually be really disappointed if we never see a Wasp in the MCU.
Also, on the topic of Marvel and women, will we see a Scarlet Witch Infinity Figure in the future? I hope so.