Even though it seems, on the face of it, as though The Dark Knight Rises may not be the ideal place from which to launch a superhero universe, we've got some ideas on how it could work, and why it might happen. read on for more...!
5. Death and rebirth. Fall and rise.
When a character falls, his rise is all the more inspirational--but generally the tradition has it that a character will rise above even where he was before the fall. This is why Lance Armstrong's post-cancer run of Tour de France victories so inspired people. And what could personify such a meteoric rise better than Batman's influence expanding beyond Gotham and inspiring a generation of heroes around the world?
Setting up something like Batman, Incorporated is totally within the sphere of Nolan's Batman universe, using the fear and inspiration behind the icon of the Bat as a rallying point--and, of course, once there's a group of costumed vigilantes out there, it could open the door for more.
The League of Assassins is kind of the opposite of Batman Incorporated, isn't it?
A well-organized group of villains or at least morally despicable people who have expert skills that you don't want villains having if they're to go unchecked. If a group like that collapses--say, by losing first Ra's al Ghul and then Bane--you're left with a world where there are a lot of very dangerous people operating in a random and decentralized way.
In the context of a comic book movie, it's basically begging for all or most of them to become supervillains.
3. Escaped convicts
Similarly, the story of Knightfall revolved around Batman being "broken" after he spent weeks rounding up all of his supervillains following an attack on Arkham Asylum by Bane. While there isn't a broad base of villains to choose from for the movie, there certainly appears to be something kind of similar going on with the escape from the prison in Gotham in this film, with Bane seen in numerous photos leading a gang of prisoners through the streets with guns.
Like the League of Shadows/League of Assassins example, who's to say that one of these guys won't try to take on Bane's mantle once he's gone, or at least take a similarly-flashy costumed identity, creating a new threat for Batman or any other hero who might stumble upon him?
It certainly appears as though Batman is building up a group of allies in The Dark Knight Rises. While Catwoman's being billed as a villain, it's clear from trailers that she doesn't particularly care for Bane and we've even seen her fight alongside Batman (one who many fans have speculated might not actually be Bruce underneath).
John Blake may spend some time in a Batman suit this movie if numerous fan theories are right--but even if they aren't, you've got at least one cop on-duty (Blake) and one who may be off-duty (Gordon) in Batman's corner as the city goes to war. If Blake and Catwoman don't have the makings of a new Bat-Army in Gotham, I don't know what does.
It's widely believed that the story for The Dark Knight Rises is broadly based on an amalgam of two comic book story arcs from the '90s: Knightfall, wherein Bane breaks Batman's back and he has to be temporarily replaced--and No Man's Land, where a massive earthquake cuts Gotham off from the rest of the country, destroying the bridges and leaving the island to fend for itself as supplies dwindle and the streets become a gang warzone.
Lex Luthor came swooping in during the No Man's Land story, using his billions to "save" Gotham, start the rebuilding process, and get himself in good with the court of public opinion (this was right around the time he was President). Even if he doesn't actually appear in the film (there's no indication that he will), Lex's existence could easily be mentioned at some point in the film, on a news broadcast or in dialog, and this makes a lot of sense because not only would it hint at the existence of a larger DC Univer but potentially tie directly into Man of Steel, the only DC feature film known to currently be in active development.
And if we went into Man of Steel knowing that Batman existed in that universe, it could make for a very different approach to the whole DC cinematic universe...!