spetznaz
Senior Fanboy Killer
I think you guys are looking at this in the wrong manner. Have a quick logical view at what B3 will be about:
i) Batman is on the run. Thus the film will be more of a redemptive process, whereby Batman has to show himself as 'good' while on the run from the police and negative public opinion.
ii) This means that the film will not have the time to bring out a complicated villain like the Riddler who would need a whole movie of his own just to develop the character well
iii) Also consider that Nolan's work is gritty genius ....he makes criminal movies where the heroes and villains just happen to wear costumes. This realistic bent instantly eliminates a lot of people like the Ventriloquist and Killer Croc as too unreal (honestly ....think of a Nolan Batman with a talking wooden dummy on someone's hand)
iv) As for Catwoman, she falls into the same basket as Robin. Interesting material, but too easy to mess up the movie and would require a whole movie (or more) to adequately develop them in a way that will fit in the Nolan universe.
v) Also consider that since the Batman will be fleeing from the cops, there is a likelihood that the criminal underground will also put out a hit on the Batman (bringing the possibility of some villains like Bane, Deadshot and Cain into play, who would fit in the Nolan universe and not require an entire movie to accomplish character development).
vi) Finally consider that B3 will be the last Nolan movie if he decides to make it a trilogy. This means he will be finishing it with a big bang, and thus will not take OBVIOUSLY silly tangents like some are mentioning here (like a team up between the Riddler and Two-face, which would be a really horrible way to wrap up the trilogy; or the Penguin which could easily make the gritty world of Nolan look like a Disneyworld freakshow).
Remember that the Batman films in Nolan's universe are supposed to be as real as they can get. As stated, the Godfather but with halloween costumes. Also note that it is the last movie and thus needs to end with a bang, and that the theme for the movie is ALREADY set (Batman on the run) which means that there might not be sufficient space for COMPLEX character development (which a GOOD reboot of Catwoman or the Penguin would require).
And finally consider that this is the movie where the Big Reveal of the Batcave will occur (since the Wayne Manor will have been finished, with the upgraded cave). Thus means there is a risk the movie would be too busy if all the ideas people are throwing about were implemented.
Also consider how Nolan thinks.
I'd say people are approaching this in the wrong way.