Rocksteady Studios pretty much wrapped up the critically acclaimed Batman: Arkham series with Batman: Arkham Knight in 2015. This also marked the studio's last major release, and we have not heard from the developer since, except for a spinoff Batman: Arkham VR release in 2016.
It is currently unknown what projects Rocksteady is working on currently, but we may just gotten a hint at it with some job listings posted on the developer's site.
As spotted by ResetEra forum member est1992, Rocksteady has posted over 20 job listings on its website, with expertise required in numerous departments, including animation, art, character, code and AI, design, dialog, and marketing.
Eurogamer notes that all of these listings reference a "AAA title on the next generation platforms". Many of them reference professional experience in creative writing in TV, comics, and novels, while others also demand a "broad knowledge of comics, novels, games, cinema, and popular culture relating to video games." Interestingly, the Lead Animator post demands a person "who is ready for the challenge of leading a team of world class Gameplay Animators towards our next 90+ Metacritic title."
Most of these job listings were announced at the start of the year but have now been made available for public viewing. Many of them are contractual positions which require a the applicant to be available for a period of two years to work on the project.
Needless to say, all of these hints point at an upcoming title, though its identity is anyone's guess. At the start of this year, Rocksteady posted images of its motion-capture support team after a test shoot which sparked rumors have previously surfaced regarding an upcoming Justice League or Superman game. We'll likely learn more about this secret project soon, if these job listings are indications of an upcoming title.