I think the Captain Marvel movies will probably go for a lot of what they would probably do with a JaneThor movie.
Personally, I think the only thing it would accomplish to do a Jane Thor movie is to get to the major parts of the Thor mythos that the movies hadn't gotten to yet, like Balder and Enchantress.
Like with Thor I don't see us getting a new Cap immediately after Evans leaves. I think it's possible either way, but I agree it's equally viable that they might just forge their own paths with their identities (Bucky already has a new one to boot).And it wouldn't surprise me if they decided to make either Stan or Mackie the new Captain America once Evans leaves. I dunno if they'll go there, and I won't be surprised if they don't, but it won't surprise me if they do. It's a viable option, yknow?