Allegedly for PC, Xbox One, and PS4
[Update #2: GameSpot has Batman: Arkham Knight coming out on October 14, 2014.]
[Update: Game Informer's new cover story has confirmed the existence of the game, as well as the platforms. Cool!]
Before you freak out -- the series is apparently back in the hands of Rocksteady. Phew. WB was all set to announce the next Batman game soon, but a GAME UK retail leak has possibly spoiled the surprise. The game is being called "Batman: Arkham Knight," and will supposedly be released on the PC, Xbox One, and PS4 this year as the "explosive finale" of the franchise.
Gameplay details are sparse, but it looks like you might get to drive the Batmobile, you might be able to play as Harley Quinn in some Challenge Maps, and Scarecrow might be the main villain. Really, I'm just glad Rocksteady is back after the monumental mess WB Montreal caused with Origins.
Batman: Arkham Knight [NeoGAF]