Warner Bros. Games Montreal, the developer of Batman Arkham Origins, is currently developing two games that will expand the DC Comics universe.
"We are a growing studio with two AAA projects in development focused on expanding the DC Comics universe in the interactive space," said the studio on its recruting page. This isn't that surprising, considering that Warner Bros. Games Montreal has previously stated that it had plans to develop multiple DC Comics titles.
Right now, it's still to early to guess what exactly these projects are. It's true that Batman Arkham Knight is Rocksteady's last Batman game, but that doesn't stop Warner Bros. Games Montreal from expanding the franchise. On the other hand, the studio could very well be working on projects related to other DC superheroes.
Source: Warner Bros. Games Montreal