I think they should forget about attempting a Justice league film. The years it would take them to introduce Green Lantern (reboot), Wonder Woman (God knows how they could do that), and Flash would just take far too long.
If they're going to do anything they should attempt a Superman-Batman film.
Rumours are that they're already fast tracking Man of Steel 2, they've got concept art for Flash already, and they want to go ahead with Wonder Woman and Aqua-man films. Apparently Green lantern isn't in their short-term plans AT ALL, even for a JL film, which is saying something about their intent, really.
If done right, Aqua-man is like the most perfect Disney-for-boys film that you could possibly do. A young kid with no friends living on the edge of nowhere discovers he is the heir to an underwater kingdom, and he can communicate on a semi-intelligent level with the wildlife. That is Disney/James Cameron 101.
It helps that he's returned to being a fucking badass over the last 2 years in the comics as well. He's the only guy who says "No." to Batman on the JL, and he punched out Superman.
I don't know what their plans are with Wonder Woman, but Nicolas Winding Refn has said before that the only super-budget Hollywood film he'd like to do is Wonder Woman. So for fuck's sake just give him the movie and 100% freedom. It doesn't matter what he's gonna come up with, it'll be amazing.
EDIT: For fucks sake, aqua-man goes to Aquilani, still