Having played through both Batman: Arkham Asylum and Batman: Arkham City, it became fairly clear that Rocksteady was building towards a climactic ending for its Bat-series. Even with critical praise and high sales, Rocksteady's vision hasn't changed, which is why the studio is ready to step away from the Bat for good with Batman: Arkham Knight.
"Anything we do is a collective decision between Rocksteady, Warner Brothers, and DC Comics," Rocksteady's Dax Ginn explained to IGN. "But it was something that we were really pushing for because we had a really clear vision for how this story should end, and the way we wanted it to end."
Ginn adds that the series is ending just as Rocksteady always envisioned it: with a playable Batmobile.
"For us I think the Batmobile is that final thing," Ginn added. "It's such a critical part of the game, the epicenter of the design, but once we've done this, I don't know we're ever going to feel like we've missed out on a critical piece of what it feels like to be the Batman. That was kind of our driving force all along."
Rocksteady is uncertain of their own future, not releasing any details on life after Batman. Of course, it's safe to say that even after the studio walks away, Warner Bros. will likely move forward with the Arkham series in some fashion, having already ventured into prequel territory with WB Games Montreal.