There’s been a presumption that the planned Batman Vs. Superman movie will lead to a Justice League film. However until now Warner has officially confirmed that. Now though they’ve not just said it’s going to happen, they’ve announced Zack Snyder will direct.
Batman Vs. Superman begins production next month, and there’s some suggestion that Justice League will shoot back to back with that movie, although that’s not been confirmed.
It appears if they’re shooting separately we’ll get Justice League in 2018, but if it’s back to back it’ll be 2017.
Specific plot or casting details have not been revealed, but it is almost certain that Henry Cavill will return as Superman, Ben Affleck as Batman and Gal Gadot as Wonderwoman. Ray Fisher is expected to make a cameo in Batman Vs. Superman as Cyborg and then appear in Justice League.
There’s no confirmation on what other DC superheroes might appear in the movie.