There's a lot of speculation that Batman will fall/die in The Dark Knight Rises. Yet Nolan has said on record (somewhere) there he will not have a Robin in his trilogy.
The man can die (maybe) but not the idea. Not the legend.
Let's assume Batman does die; or at least gets too old for this sh...tuff.
Who then will replace Batman? Joseph Gordon Levitt?
How about Batgirl then? Barbara Gordon has already appeared in Nolan's trilogy in the finale of The Dark Knight. And the filmmakers (specifically Nolan as Director) really went out of their way to not show the actress' face. As if he had bigger plans for the future of this character, and knew he'd need a bigger actress for her later on. Watch the scene again with that in mind and you'll notice what I mean.
Babs is about 12 in The Dark Knight. The Dark Knight Rises will take place eight years later. Making Babs around twenty 'now.'
It's already pretty well established that Nolan's trilogy is about Jim Gordon and Bruce/Batman, not just Batman. What better way to culminate the trilogy than by combining the two?
It's as if Batman and James Gordon had a baby together, and she will be the future of Gotham City. That would be one hell of a way to wrap up a trilogy, wouldn't it?
Other than the obvious use of Bane (and with Nolan is it ever really about the obvious?) The Dark Knight Rises actually has a lot of elements of 'girl power:' Talia al Ghul, daughter of Ra's, has likely taken up her father's mantle. Catwoman (nuff said.) There's even talk that Selina's 'sidekick' Holly Robinson (another daughter figure) will appear in The Dark Knight Rises.
That's a lot of girls/daughters for a boy's action flick about a guy who dresses as a bat and a good cop working in a bad system.
Will it happen? Will Batgirl appear in Nolan's trilogy? I would love it, Nolan could pull it off, but even I doubt it will happen.
Although...Batgirl did appear in Batman and Robin, the only other live action appearance of Bane. Could Nolan be hinting at something with Bane's inclusion? Could the femininity of Batgirl be the polar opposite of the musclebound steroid infused He-Man Bane, and the only response to the brute male force that has hit Gotham City in this, the last chapter of Nolan's bat-trilogy?
With Nolan, expect the unexpected.