So, it's been announced a multiplayer mode is being developed by a separate studio.
It's a 3 on 3 on 2 mode. The teams of 3 play Joker's gang vs. Bane's gang in a third person shooter mode where they try to whittle down the respawns of the other team and hold command points. Once per game, the team in the lead will spawn Joker or Bane and the first player to get to a chosen location gets to play as them.
The team of two is Batman and Robin, trying to fill up a bar that rises when they coordinate their attacks and use varied takedowns, but plummets when they're taken down by thugs.
Done right, it could be a surprisingly fun multiplayer suite like Assassin's Creed. Guess we'll see.