After Bane is apprehended, killed or whatever it's revealed that during Gotham's destruction (or whatever has happened) that the Joker escaped Arkham.
Cut to this,
0:20 - 0:32 (disregard the Penthouse/Rachel/Batman bits)
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Basically set the scene up as The Joker and a few henchmen back in Gotham. Change some dialogue around a bit (make the thug say something else).
Main idea here is, any unused footage or dialogue you have of the Joker that would make sense to use, USE.
Then, to tie everything up, you gotta have a final interaction between Gordon and Batman. Something reminiscent of Begins and TDK, but still different enough. A member suggested Batman saying "thank you" to Gordon and if Gordon does indeed inspire Bruce to get his Batman mojo back ("we were in this together, the Batman must come back, he must") I think that would be great.
These two scenes would establish three things, by the end of the film Bruce finds that he needs both the charity, philanthropy side of "Bruce Wayne", the side his father would be "proud of" and also, the Batman persona. The silent guardian, the avenger of the night that fights the criminal element of Gotham City. It would also play with the Rachel/Selina aspect of Bruce's personality. Rachel/Catwoman, Bruce/Batman, Ying/Yang. The second thing it would establish is the relationship between Gordon and Batman, the unrelenting heroes and defenders of Gotham city. The third and final establishment would be that Batman has transcended from the character that we saw in Batman Begins, a whole character arc. This Batman understands what it is to be Batman (he's gotten wise to it all) and that he will need to do this for the rest of his life (especially now with the Joker element back into the picture and the fact that Gotham will always be a target by future enemies).
Have a couple of iconic, epic lines from either of the two that makes sense for the title of the film (Batman's rise to character) then cut to,
THE DARK KNIGHT RISES