From the looks of this job listing it seems there's new Diablo content on the way. Blizzard is looking for an art director on an "unannounced project" clearly labeled "Diablo". Given that we're only about three years into the Diablo III cycle, the position is probably for work on the next expansion, though no console or release window were given. The first and so far only Diablo III expansion Reaper of Souls debuted this past March and was very well received.
The job requirements include an enormous amount of skill and experience and a strong passion for and understanding of the Diablo series. If you'd like to apply, hit up the Blizzard career posting.
via GameInformer