There's not really anything to say they will even use Green Lantern, I thought the film was decent, but as I understand it, it was a flop. Bale not returning as Batman hurts the potential of the JLA film considerably. He's been the most consistent actor in any DC comic adaptions, which to be honest have been fairly sporadic. Sure Reeves got in one more superman film, but only his first 2 are noteworthy. Bale got in 3 solid, critically acclaimed films.
I like the new superman, but he hasn't established himself enough to support a new Batman coming into the mix. The Avengers had consistent, solid films, only the hulk had any kinda inconsistency, but most agree that hulk was the best thing in the movie.
DC need all the cast to have had at least 1 ideally 2 solid films before they consider a group outing. Basically they need to copy the marvel films formula if they wanna succeed in my opinion.