Alrighty...Here is my current theory in progress about Clara Oswin Oswald. I think it all hinges on her last words in Asylum of The Daleks and in Snowmen. In Asylum she says "run your clever boy..and remember me" and in Snowmen she says almost the same-but it has a key difference-she says "I remember" as if she was remembering herself as a past iteration that had met The Doctor.So-What if her last words in Asylum aren't so much sentiment as directive.She's a genius who can hack Dalek tech.What if The Doctor running and escaping and remembering her are part of her plan to escape both her Dalek form and the Asylum? The air is filled with nanotech that is Dalek in origin. The Doctor no longer has his bracelet on-he put it on Amy. What if she hacks the nano tech-transmits her sentience into them in some fashion and hitches a ride on them as they hitch on him?But of course it's a memory of her and as the TARDIS hurtles through space and time those multiple iterations of her contained in all that nanotech get scattered. That naotech can and does reform dead bodies,it does take over living ones,and each has faint memories of who they were-remember Clara as she dies in Snowmen saying "I remember". It could be that Oswin is the source and that there are multiple Claras out there in various times.And it could be that Oswin knew that would be a likely outcome of her plan-but she also knew the Doctor would not only run and escape the Asylum but that he would travel all of space and time and that they might well cross paths again-she may have been hoping and banking on it.Then there is 21st century Clara who says Ì don`t believe in ghosts. She may well be a ghost in a machine that has become a living memory with multiple iterations scattered across time rather than reborn after every death.some of the iterations still live and some have died.But Oswin in her genius has escaped The Daleks, and asserted her humanity across all space and time.I could be wrong or I could have to tweak parts of this as Moffat reveals more but that`s my best guess for now.