This soon after Batman Begins, that's bound to be a controversial move, and if the first movie back from the Nolan series isn't a blockbuster, then it'll be a huge black eye for Warner and a failure for the filmmakers. What are the biggest challenges the next filmmaker will face? We've got a list--and some ideas for how to offset them a bit.
Finding a voice
The problem: Batman is, as has been pointed out over and over, a character that thrives on reinvention. Still, the character has worked the best in basically one or two ways over the last thirty years. Frank Miller has used him as a deeply damaged person with occasional shades of sociopolitical commentary, while most other creators have crafted something more in the Neal Adams model--the dark, brooding avenger of the night who does this because he's better than anybody else at it, and couldn't forgive himself if he didn't.
Of course, both of those takes were central to Christopher Nolan's interpretation of the character, and the more shiny superheroic, campy version that was popularized by Adam West was adopted by Joel Schumacher in the '90s, to disastrous results. Making something that resembles the comics right now, or resembles the best and best-received film versions, will inevitably seem like little more than a rehash of what Nolan has done.
The solution: Batman, Inc. One of the big ways that Nolan has distanced himself from the mythology and the feel of the comics is that he has intentionally and emphatically stayed away from the bat-family. If Bruce were to see results in what he's doing, and conclude that Batman could be a powerful symbol outside of Gotham as well as inside, it could go a long way toward changing people's perceptions of the franchise and the characters. Think of it as Scott Snyder's Batman (Nolan's films) versus Grant Morrison's (the new guy).
Making him a team player
The problem: It all comes down to Justice League again. If DC is going to craft a cinematic universe to rival Marvel's, Warner Brothers needs to create a world in which Batman seems like someone who might credibly be able to play well with others.
Most of the public at this point know Batman as a reclusive loner, a lone guy who hangs out in his cave and really only relates to Alfred. The fact that both Tim Burton and Christopher Nolan used this characterization, and that most modern comics use a variation of it, hinders progress because there's so little source material to refer to, in order to learn how to do it right.
The solution: Justice League Unlimited. The DC Animated Universe, which started when Batman was launching out of the popularity of the Burton films, is a great comics-to-screen adaptation of a Batman who can tell those quiet stories about organized crime but is just as at home with a world-threatening alien invasion. Unlike Super Friends or even Batman: The Brave and the Bold, Justice League and Justice League Unlimited never took the DC Universe for granted--they still occaionally confront the oddness of Batman hanging out with Enlongated Man or Booster Gold--and they never disappointed. Look to the DCAU for inspiration and you're unlikely to fail.
Coping with the DC Universe
The problem: While we're at it, how will Batman, a guy who's the pinnacle of human achievement but in a very real world where human achievement is limited by human limitations, handle it the first time he encounters one of these super-people? It's a difficult scene to write and to shoot, and it's certainly not something that the average moviegoer, most of whom don't read comic books, will cope with easily.
The solution: DC: The New Frontier. If you're serious about integrating Batman into the DC Universe, what you really need is to set him up with a powerful figure at some point relatively early in his film. You don't need to necessarily make a Superman-Batman film, but what you need to do is to have him encounter Superman (or Martian Manhunter, in the case of The New Frontier) and form some kind of bond with him. If you establish in Batman's own film that he exists in a world with these people, and that he trusts and can operate with some of them, then you don't have to explain that in Justice League, when there's a lot of other stuff going on. The last thing you want is a PS, a la the Marvel movies. It worked for them, but it's a dicey game to play with a character like Batman, about whom most people think they know so much and can anticipate his reactions.
The problem: Batman's costume has had some truly awful big screen iterations, and you can't afford to evoke the vitriol of the fans with your first teaser. People will already be skeptical of whatever comes after Christopher Nolan, so those initial promotional images and set photos have to set a tone.
The solution: A little from column A, a little from column B. You have to really look at everything that's worked in the past, and at everything that hasn't, and you have to come up with something that's as simple and iconic as the Tim Burton Batman, as practical and believable as the Nolan Batman, and ideally that incorporates the general look and color scheme (the blues and grays) from the comics in some way, just to keep visual consistency from the comics to the screen and to play on the idea that this isn't just "new," it's a reinerpretation of a classic. You want this to be like the new Mustang.
The problem: Every fan thinks they know who would be the perfect Batman, and nobody can agree on who that might be. Often, fans disagree passionately and sometimes they can't find it in themselves to be particularly nice about it. If you cast the wrong actor, it can torpedo the film completely, but if you cast the right actor and the fans decide ahead of time that he's going to suck, you've got an uphill battle on your hands to sell the picture.
The solution: Just own it. Nobody you cast is going to make all of the fans happy, and honestly it'll be hard to find anyone who makes most people happy. As Christopher Nolan said, this is one of those cases where you just have to make the right choice, make a good movie, and let the chips fall where they may.