As to how Clara is going to be - and why she keep being reincarnated - I'm not sure. I actually haven't seen many theories online, which is odd.

Much as it's something that gets rolled out whenever there's a new character mystery - maybe she's a character from the Doctor's past trying to catch up with him. A Time Lady maybe using Time Lord tech to connect with this bloodline throughout time? Iffy, I know, but a thought.

There's also the idea that she's Wilf. Remember? The Doctor kept bumping into him and Donna because it was destiny that Wilf would be the end of his 10th incarnation. The same scenario seems to be happening now, but with the same personality in different bodies. Perhaps something timey-wimey in which that personality must have an integral part - a fixed point in time?

Yeah, I'm spitballing. Any other thoughts?