There's a fuck-ton of things happening in this movie. I have faith in Nolan's ability to create one narrative out of many, many different characters, but it's driving me nuts wondering what's going to happen and how R'as, Bane, and John Blake play into it.
That symbol being chalked onto the surface of something looks strikingly similar to Nightwing's emblem.
That's the one thing I take away from the trailer that just confuses the shit out of me. It's clearly meant to confuse people into thinking it's an unfinished batman symbol, but it's not at all.
Nolan is really drawing inspiration from the comics with this film, though. No Man's Land and the earthquake with gangs overrunning Gotham, Knightfall and the potential of "breaking" Batman and the other potential of someone standing in place for Batman while he heals, and The Dark Knight Returns showing Bruce come back years after he "retired" to finish his job as protector of Gotham.