In a recent interview that Cliff Martinez did with Lost in the Multiplex, he casually revealed that he is working on the next Far Cry 4
According to VG247:
According to Martinez he is working on “a video game called Far Cry 4,” along with a new TV series from Steven Soderbergh.
Ubisoft has yet to announce the game as being in the works, officially, but considering the success of the last outing, Far Cry 3, it’s not much of a stretch.
Official Source + Full Interview: http://www.lostinthemultiplex.com/extras/features/item/4252-the-soundtrek-interview-cliff-martinez.html
http://www.vg247.com/2013/10/08/far-cry-4-in-the-works-according-to-composer-cliff-martinez-report/