I think they could be referring to the end of A Dark Knight when Batman is talking to Commissioner (now LT.) Gordon saying he can be whatever Gotham needs him to be, and at the end of the 2nd film Batman is basically the "villain" and now he will return when Gotham has taken a turn for the worse, when Gotham "needs" him again.
Hence A Dark Knight Rises when the city is fallen (teaser poster)
I saw the preview to this movie in the harry potter premier and started jumping out of my seat squealing with joy! I <3 the Dark knight and hope this next one is just as good as the last! I've heard that the main villains are Bane and Catwoman. Catwoman will be played my Anne Hathaway and I don't remember who's playing Bane but he's the one in the backround at 1:23. I also heard confirmation that an actress named Juno Temple will be in The Dark Knight Rises with the role of a "street smart Gotham gal" Which could mean tons of different characters. Considering the actresses looks and personality I have my fingers crossed for a Harley Quinn but I can't be sure. A lot of people are saying she'll be Stephanie Brown (even though that wouldn't work well since we haven't even had a Robin in the movies yet) or she might be playing someone else. I'm not sure but what do u guys think?