Following the massive flop of Suicide Squad: Kill the Justice League, there have been occasional rumours that Rocksteady is ready to tackle a new Batman project, and there is even a job listing that supports this. More specifically, it appears they will be adapting the animated series Batman Beyond, and now new information has emerged claiming to confirming this, complete with a leaked image.
The rumour suggests that Rocksteady was already working on such a project, but that it was shelved and restarted with a different focus. It is set to take place several years after Batman: Arkham Knight, but is only loosely based on the Beyond series, featuring a slightly less sci-fi aesthetic while certain parts of Gotham still retain the classic Gothic style.
Batman himself, Bruce Wayne, is in this game as an older gentleman who has trained a new, young talent named Terry McGinnis. This allows Rocksteady to explain why you must once again learn what Batman already knew in the Arkham trilogy. The beloved Nemesis system has apparently been dusted off for this game, and the villain will be Derek "Blight" Powers.
Three images have leaked and are that classically blurry way leaks used to be fifteen to twenty years ago. As of this writing, you can check them out here.
As usual, this is just a leak, and it could very well be fabricated. But Rocksteady does seem to be working on a new Batman game, and Beyond is a popular series that also makes it easy to design the story as a natural continuation of the Arkham saga, so it's not impossible at all that it's true.