I don't recall where I read this particular theory, but as silly as it is, and as impossible as it is, I thought it was the most interesting idea.

The theory: somehow, some way, Clara is actually the 12th Doctor, but does not remember her life as him (the theory talked about the whole fob thing that the 10th Doctor had, that watch he had to open to remember who he was a couple of seasons ago).

Yes, this theory is nutso, but I just think it would be fun to see the Doctor regenerate and end up a woman. I figure we'll see a woman version of the Doctor (and even a black incarnation) before we ever see a Ginger version of the Doctor.