Warner Bros Montreal is working on a new IP and is in the process of hiring a lot of new faces to make it happen. The developer is best known for Batman: Arkham Origins, a spin-off of Rocksteady's successful series.
On their jobs page a listing states the developer is working on "a new IP project for next generation platforms". Another listing says they are looking for someone who would be "responsible for designing and driving development of specific features or systems for an open-world action game." There are further references to the use of Epic's Unreal Engine, suggesting the new game is being made with that.
They are currently looking for an art director, game designer, QA lead, level designer, a technical director and a UI programmer among other jobs.
Batman: Arkham Knight - released last week - is the final part of the Arkham story and the end of Rocksteady Studios' trilogy, but more Batman games are expected to be made under the Warner Bros banner.
Given their history with the series, WB Montreal seemed to be one of the developers most likely to inherit the cowl. However, this new IP development might suggest otherwise.
New IPs are always good to see, but new IP doesn't necessarily mean an original property. It could also refer to a new game series based on an existing franchise, say if Warner Bros wanted to expand on their Batman success with more games based on DC characters.