Aaron Helzinger had some serious anger management issues, so a doctor removed his amygdala, a part of the brain that controls emotional responses. But the surgery resulted in him becoming easily manipulated, and just as prone to fits of rage. Until somewhat recently, when he became largely cured and an ally of Dick Grayson, nearly every one of Amygdala's appearances have involved another villain convincing Amygdala to attack Batman.
Pros: A medical treatment gone awry could work in the movie universe, realism-wise, and Batman really hasn't dealt with an opponent who was purely a physical threat yet.
Cons: He's kind of a poor man's Hulk. Childlike mind, anger issues, freakishly strong (though I've never been clear how strong Amygdala is, relative to Bane or Killer Croc or anything). And you certainly can't have a whole movie based around him as the villain, since he's just a strong, not very bright guy.
How I'd do it: You'd have to have another villain calling the shots.
Casting Guesses: Some huge wrestler? I have no idea. Or Dalip Sing, the huge guy from Get Smart and The Longest Yard remake, who I just learned is also a wrestler.
Verdict: I'm tempted to say no chance, but he's the kind of guy who could get a tiny background appearance like Zsasz had in the first movie.
After The Scarecrow, Ra's Al Ghul, The Joker, and Two-Face, who should be Batman's next enemy in the Batman Begins/The Dark Knight series? Well, as of now we know that Tom Hardy will play Bane and Anne Hathaway will play Catwoman.
Check out the master list for all the villains covered. I've pretty much run out by now. Obviously, there are more Batman villains, but not any of significance that I know of. As of February 2009, no one is confirmed as a villain. Not the Johnny Depp Riddler, not Phillip Seymour Hoffman Penguin, nobody.