I don’t see it ever happening, at least not the right way. The right way to do this movie is the way the Avengers did their movie. You have a movie about each character and prelude to 1 big movie with all the heroes combined.
DC hasn’t giving any indication that a Justice League movie is in the works. They would’ve started showing signs of it at the end of Batman. That’s the best way to do it. Another Justice League character, Green Lantern, had no Justice League type ending either. With a new Superman movie coming out, I’m not expecting it either.
The amount of work that would go into it now is a waste of time. You would have to make a movie about each character and each ending would give hints of a Justice League movie coming. That’s the best way to do it.
However, you can always just make a Justice League movie. You can do the way the cartoons do. You make a crisis and just send all the heroes there to save the day. Then at the end they realize that together they are better off and start the team.
So yes, it’s possible, but unlikely. After the way the Avengers did their movie. After all the hype for years it created, doing it the cartoon way isn’t as profitable. That’s what these companies all care about. The fans really don’t matter in end and it’s a sad truth. A Justice League movie will be awesome, but like I said, I don’t see it happening anytime soon.