Originally Posted by
Winterland:
“I think she is a time lord of some description. I would love if she was an incarnation of the Master that keeps hopping around time to avoid capture and tries to stay close to the Doctor as cover. but i think that's my imagination running away with myself!
”
I wouldn't be too disappointed if this were the case, but personally I hope it turns out she someone/something related to the Doctor that hasn't been seen or heard of before.
I would like River to become new Doctor Who mythology. It's all very well pandering to the fanbase already there, but what about creating new myths for the future Who fans? I think SM is quite likely to do something like that.
He's already created some iconic monsters himself, and they could be back in future incarnations of Doctor Who, so why not create a character that would have people in another 47 years saying: "That new woman, Qxytlkj. I bet she's really River in disguise", in much the same way that people want the Master back now, or the Rani (though god only knows why they want her back...)?