Hmmm... this is fascinating and a bit disturbing. I think the issue that troubles me is the struggle of Mary and her gender role - about how wrong it would be if she was a female. This contrasts very startling with the bookverse Peter, who is very right as an archetype. But this is a very, very different universe.

I think this version of Mary is on a collision course which she won't get off of (unless, well, she ends up walking into a magic world...). I would wonder quite seriously how Narnia will impact her - it won't be positive when she comes back because she'll chaff even more under England's society. I would not be surprised if she started to identify as an asexual transman (or at least fell into that subculture in the fifties... can you imagine how horrifying that could be?).