These new Batman: Arkham Knight rumors are awfully interesting, and filled with tons of MAJOR SPOILERS which you may want to avoid. It is however worth checking out, despite the fact that we can't confirm this, so you may wanna take this rumor with a hefty dosage of salt. Anyway, below is a Screen Capture of the 4Chan user's original post, so you can can click on the image to see the guy's entire post covering everything from plot details to characters.
Thanks to @LEVITIKUZ for the heads up
In the explosive finale to the Arkham series, Batman faces the ultimate threat against the city he is sworn to protect. The Scarecrow returns to unite an impressive roster of super villains, including Penguin, Two-Face and Harley Quinn, to destroy The Dark Knight forever. The next game in the hit "Arkham" series will be released on the PS4, Xbox One, and PC.