I can't help but feel that while it is clearly successful enough to warrant a sequel, WB have decided that the best way to maximise income is to bring in the assured box-office pull of the Dark Knight. And simultaneously relaunch that hero on the big screen.
In doing so, they are neither replicating Marvel's approach with the solo movies leading up to an Avengers/JLA epic nor are they taking the gamble of one film being used to introduce and launch all of their heroes at once. This approach strikes me as very sensible and shrewd and if this film is a hit, it will springboard new Batman films and probably set up a JLA one.
You know, that's a thought. I've been wondering what approach they could take that was neither a copy of Marvel's (solo hero films followed by mass team-up) nor a simple inversion of it (mass team-up followed by solo films). Maybe what they could do is the equivalent of a team-up comic: Do several Superman films, each of which teams Superman with a different guest hero. So that Batman is introduced in the second Superman film, Wonder Woman in the third, etc., and then it eventually builds to a JL film.
I'm not saying that's what I think they are doing, but it just occurs to me as something that might be suitably distinct from the Marvel approach.
Yes, that could work too. I'm not sure that they will do that though - I think Batman is different from their other gallery of heroes in that he is a proven box office draw in not just one but two series of successful (financially anyway) movies. No other comic strip hero has achieved that yet (Spider-man is on his way, admittedly). I still tend to the idea that in this movie Superman is getting a boost from him as much as the other way round, even if this is an as yet-unseen version of Batman.
Of course, if the next film follows the Dark Knight route of the sequel being way more successful than the first in the series, then Superman is well placed to springboard Wonder Woman etc onto the big screen. And, as you say, in a totally different fashion to how Marvel have done it.