Bill Dungsroman wrote:

Personally, I don't think they're even greenlighting superhero films without at least one sequel in ink (as in, contracts to the director, actors, etc.). So they make the origin first film, hoping for crossover success and placating the fans (by, naturally, giving them what they pretty much already know) in a tug-of-war between the two (X-Men handled it the best, I think). The second film is where they can be more original with their storylines; you don't risk alienating the comic fans with new storylines after the origin has been established more-or-less properly in the first film. So, same cast for DD is virtualyl a gurantee, except different villians.