Yeah, it's shelved for now and Christopher Nolan
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Still, recently at the Comic-Con during Superman screening, Zack Snyder said:
“Superman is the jewel in the DC crown,” Snyder told the Hall H audience of about 6,500. “And really what we’re trying to do is get his house in order, and then who knows what’s possible.”
It sounds as if he's planning something big. Another fake hope or plausible rumor, time will tell.
Nolan was the best man perhaps but his refusal just jeopardized everything. Hopes were high when Nolan was involved behind writing of Man of Steel. Now, there no much news for it. If it do happen, I doubt it'll be before 2014 or 2015.
Personally, A JLA movie needs much works. Not in terms of presenting solo Wonder Woman/Flash movie first but to present a strong enough villain. Let's admit it - the scale will need to be really high and it can't be a repetition of Avengers either. So, it's far from easy to make a JLA movie. Much harder than making an Avengers one.
Speaking of Avengers and Marvel:
Iron Man 3 has also been trailer-screened at Comic-Con.
Wolverine Origins and X Men First Class 2 are also in production by 20th Century Fox.
Fox are also trying to reboot Fantastic Four and Daredevil. Though, Marvel is trying to keep Daredevil's rights to themselves.