Warner Bros. Interactive is currently getting ready for the release of a new Batman: Arkham game this year.

VG247 contacted John K. Martin , Time Warners CFO and chief administrative, to see if this was all true and he responded:

During the call, Time Warner’s CFO and chief administrative officer John K. Martin stated, “And we also have a strong games release this year, which will include the next release in the Batman Arkham franchise. So all in all, we expect Warners to post another very strong year in 2013. And with a little luck, the year should be as good or maybe even a little bit better than 2012.”
This means that the new Batman: Arkham game could be due before the end of the year or the beginning of 2014.

Source: VG24/7