Batman: Arkham Knight's December DLC will arrive on December 22, Rocksteady Studios has announced. The expansion is called Season of Infamy, and, among other things, it delivers Batman and Batmobile skins based on Christopher Nolan's 2008 Caped Crusader movie, The Dark Knight.
Rocksteady has also posted the final "Arkham Insider" video feature 2015. This one shows off the Season of Infamy content, featuring insight from a number of developers, including studio head Sefton Hill.
Hill also talks about saying goodbye to the Batman Arkham series, though you'll notice he does not outright 100 percent confirm that Rocksteady won't ever make another Batman game. As for what's next for Rocksteady, whatever it is, it may feature multiplayer in some way, according to a recent job listing.