First things first, they need to get out a quality sequel to Man of Steel ASAP. As I understand, Warner Bros. even before the film was officially released already fast-tracked the sequel, so I wouldn’t be surprised if we saw the sequel in 2015. But, really, they need to get something out next year that is consistent with this universe.
I agree that it’s too early to do a Batman reboot, trying to run with Christian Bale or JGL as Batman isn’t going to work. However, Batman is well enough established that he really wouldn’t need a movie prior to Justice League. I could see them doing a little name dropping of him in some other film and leaving a lot of anticipation for Batman on Justice League. For instance, Bruce Wayne could be mentioned as a business partner with Lex Luthor in the Man of Steel sequel and be given a little screen time as just Bruce Wayne, not unlike how they had Harvey Dent in the Tim Burton Batman with the intention of having him be Two Face later and then scrapping it for the campy version by Tommy Lee Jones. They could also drop Batman’s name in comparison to other heroes, talking about how he’s a vigilante and above the law, essentially just letting him be an established hero. IMO, he really needs to be a bit older when he’s in the Justice League and not fresh out of an origin story, so that could work really well.
Hell, have him working with Lex specifically because he believes he’s corrupt and going to use the Kryptonian technology for nefarious reasons, so he’s stopping him internally while getting his own hands on it to help establish the Justice League, use it to build the Watchtower, and he could be a Nick Fury type character who has the experience as a hero, realizing they could do more together and gathering the people together and at the end of the sequel, he and Superman know who eachother are and he invites him to join the club.
I really think they need a Wonder Woman. That’s one place where DC can get a leg up on Marvel because, while Black Widow is cool, she’s not a hero on the level of Thor, Iron Man, and Captain America. It would be a bit of a risk, but DC having a successful female hero as the solo lead of a film would be cool. She definitely needs a lot of modernization, even moreso than in the JLU cartoon, to work as a film. They need to take the same sort of approach to her as they did with Superman in Man of Steel, pretty much just not using the name Wonder Woman, letting it be dropped once, and just having her go by Diana or whatever.The biggest problem, though, is I don’t think Greek Gods, as is, is going to work, and the other obvious solution would stink too much of copying Thor.
I’d love to see Green Lantern done right too, but I’m not really sure how. I think the biggest problem with that film, other than the awful script, was the selection of basing it on Hal Jordan. While he’s the best known Green Lantern, he’s not going to work well and, frankly, I think his character would have too much overlap with Flash. I think JLU made a wise choice with Jon Stewart, his character worked well and added some diversity, but they could pick any of them. Hell, they could do a sort of partial reboot by skipping the origin, having another lantern for some reason, and picking up with Sinestro as the villain.
As for Flash, I’m not sure how he’d do in a solo movie. He probably should get one, but only to help establish his character and so he could be thrown into the movie as young and unsure of himself. At least in JL cartoon, a lot of of his early characterization that I think worked well was that he was around established heroes like Batman and very powerful ones like Superman and he didn’t feel like he had much to contribute. Give him a decent origin, hopefully better than “splashed with chemicals” which I think is his usual origin, and let him learn about his powers and that movie, but kind of let him be the internal eyes for the audience in awe of the other JL members. If they don’t think they could pull it off, they’re better off doing nothing and just leaving his origin untold than throwing him as an extra hero in another film, I think that’s one of the mistakes Marvel made, particularly with Hawkeye, just throwing his name out there, not giving us a reason to find him interesting then, worse, having him mind controled for half of the Avengers film.
Either way, it looks like a Justice League movie is probably best put off until at least 2017 or so, which makes me sad.
ETA: I haven’t watched it, but how is the Arrow show going? Could they possibly use that as partial lead in to a Justice League movie?