Honestly, I don't know if there can ever be a Justice League movie. Correct me if I'm wrong (and I know you will) but what JLA fans want is exactly what Marvel is doing with The Avengers -- a bunch of solo character movies, establish the universe and the continuity, and then launch a superhero team extravaganza. They want good actors of the appropriate age, not a bunch of young and pretty things. They want it to be a solid effort, not something hastily thrown together for a late summer cash grab -- which is all Justice League Mortal seemed to be. (No offense to all involved, but hey, we're on the outside looking in here.)
Reportedly, this is what Warner Bros now wants to do -- but I think they missed the boat back in 2005 because of a small, independent film you might have heard of called Batman Begins. I think Christopher Nolan effectively killed the Justice League by setting up a Gotham City that hadn't heard of superheroes or comic books, and would never lend itself to the crossovers that Marvel is meticulously setting up. You can't cry foul, since that's exactly why we liked Batman Begins and The Dark Knight, but it automatically removed a VIP of the League.
So, what do you do? Leave Batman out? That's practically heresy. The only option is to recast him, and create a flashier Batman that exists solely in a universe with the JLA. While I think that could work, it's hardly the streamlined approach that Warner Bros could hope for -- and it's going to wreck havoc with the brains of mainstream audience members. Comic book fans are used to alternate universes and Ultimate line-ups; precious areas of our brains are devoted to keeping it all straight. (Seriously, guys, we could probably cure cancer if we freed up the brain cells devoted to this arduous task!) Losing that mainstream audience is fatal -- let's face it, we nerds weren't the only reason The Dark Knight made a gazillion dollars, it was the ordinary people who recognize Batman, and dig a solid movie about him. I don't think those people are not going to accept anyone but Christian Bale in the role for a very long time.
Luckily, a very long time is what, at the moment, the Justice League has. Despite all the summit meetings and secret superhero plans, we have yet to see an origin movie for a DC character. (I'm leaving Superman Returns out of that equation -- it wasn't an origin movie, and even if they never got around to rebooting him, nothing about it removes Superman from a JLA line-up.) Wonder Woman, the Green Lantern, the Flash, even Superman -- everyone is just sitting, waiting, twiddling their thumbs as their scripts are rewritten again and again. As soon as someone, like the Green Lantern or Wonder Woman get close, the whole project vanishes. It's really frustrating to be a DC fan these days.
The delays pose an interesting thought -- could Warner Bros and DC take so long that Nolan's series might be complete, and audiences would be comfortable with a new Batman? And might not that be the best thing anyway, when you have The Avengers looming so large? Again, you have to think of those mainstream audiences, who are probably just going to be confused and disgusted by competiting franchises, and might begin avoiding both sets of superheroes.
I've posed a lot of questions here, and offered up a bunch of unsatisfying answers. Admittedly, as a Marvel girl, I don't have a lot of interest or investment in the JLA. But like any comic book fan, I want to see the properties done right because the fans and the characters deserve it. I'm at a loss as to how Justice League ever can be. But given that negative fan reaction supposedly sunk Justice League Mortal, I think it falls to the fans to decide the fate of the JLA -- and what better place to do it than right here? It's all yours, readers.