My bet is, whoever she is, she's there to be used as DC's Un-Reset button in case this Revamp doesn't work out for them.
I'm not so sure she or anyone else can be that. I really think this is it. If this doesn't "succeed", and I'm not even sure what the gauge for that is. DC will still be number 2 at least, so unless they beat Marvel is it a fail?
If they reset what has already been reset everyone will cry foul simply because of the huge media surge that came with the reboot. Even if they claim that it was the plan from the beginning, but then they seem disingenuous from the beginning. No, I think this DC has put all their eggs in the basket, of course, nothing much has changed too dramatically (is anyone griping about Superman anymore? I don't think so) except the numbers on the cover of the book.