The story between Batman and Rocksteady Studios finished with Arkham Knight. Officially, Rocksteady pretended to start a new project far from the Dark Knight after that game, but the Bat makes money and Warner will have plans to continue the license with or without Rocksteady. A new rumor states that a new Batman game could in development.
A new era would begin in this development. Batman would be represented by Damien Wayne, the son of Bruce Wayne. Gotham would be bigger and would show more signs of population than before. The plot would invite the players to live as Batman for more of one single night. There is a chance to see day/night cycles in Gotham. Batmobile is not confirmed, but Damien could drive the Batcycle. As the player progress in the story, the Batcave could be upgraded. Sadly, there is no info about the developer.
I am a big fan of Batman, but Gotham felt lifeless in Origins, Arkham City and Arkham Knight. It’s a great point if they pretend to fill the city with life. I highly doubt that Rocksteady is behind this, there are more chances to see Warner Montreal developing the new Batman entry.
Like always, take this with a cautious amount of salt.