Justice League - coming to theatres in 2015.
So, based on a conversation I had yesterday, this is my idea for WB/DC Comics to follow Marvel’s lead and make a Justice League movie by 2015.
Superman is already getting a new movie, in a new universe, arriving 1 year from now. They could start laying the groundwork with it.
Green Lantern would be the Hulk of the group, having had a less-than-well received film to introduce him to movie-goers. They could easily put John Stewart as the GL for Justice League, or Kyle Rayner, or even Hal Jordan (possibly recast?).
They need to make two solo movies to release starting as early as late 2013 through 2014, a la Captain America & Thor. I would suggest Wonder Woman, and possibly Flash or even Aquaman. A good Wonder Woman movie should be easy; the animated one from 2009 is a perfect template. Flash or Aquaman could carry solo movies, as well, I think.
By 2015, they have re-established Superman, and had solo films for WW and Flash/Aquaman. If necessary, they could do a Batman reboot film to establish a new version of the character, released in late 2014 or early summer 2015. Personally, I feel Batman would be a much harder character to integrate into the Justice League well. Currently, the majority of movie-goers are used to the Nolan-era Batman films, which are set in a very realistic world, where things like super-powered characters and invading alien armies don’t really belong. To include Batman in the Justice League, they would really need to make a Batman who inhabits a world closer to the comic version, where magic and super-powers can actually exist.
With or without a new Batman film, WB could release Justice League as soon as 2015, starring Superman, Wonder Woman, Flash, Aquaman, a most-likely new Green Lantern, & the new Batman. Using the “New 52” Justice League as a template, they could introduce Cyborg, somewhat familiar to audiences, thanks to the Teen Titans animated series, and use Darkseid as the big bad.

