Latino Review is reporting that Justice League will follow Batman vs Superman... immediately. Like, they'll shoot the films back-to-back. BvS will end on a cliffhanger that will be resolved in the next film, possibly coming in 2016.
This makes a lot of sense and puts a lot of things into perspective. It definitely helps us understand why there are so many character names being thrown around for Batman vs Superman. I was recently told by a very, very trusted source that the role Jason Momoa was up for (but is currently denying) is definitely Aquaman, but it's essentially a cameo setting up the next movie. Momoa's denials today could just be a smokescreen intended to protect the surprise nature of the cameo, although if the films are shooting back-to-back we'll know soon enough.
I trust Latino Review's sources on this one, and even if the movies don't shoot exactly back-to-back The Hobbit style (they clearly are not because they didn't shoot the Hobbit movies in chronological order, but rather as one big movie) I think that they'll roll almost right into Justice League. But who will direct? Zack Snyder will likely be tied up in post on Batman vs Superman; will the break be long enough for him to finish the movie or will a new director take the reins?