http://www.polygon.com/2015/10/10/94...ecure-r-rating
This could, potentially, be the first R rated Batman of any kind. Now, as the title says, they've merely been given the green light; that doesn't mean that they will to do it, as producer James Tucker said.
Still, if any Batman product would be rated R, or be the first to open the door to more of these (besides Gods & Monsters), it'd be The Killing Joke. If this does well, then this could have an influence on even future live action Batman movies (not saying that it has to, tho).