Blizzard has posted a job listing looking for an art director for an unannounced project, although that same listing clearly says Diablo.

The posting doesn't list any specific consoles, and the requirements seem pretty standard. It does, however, list as one of the "Pluses" for any applicant: "A passion for games with a deep understanding of the Diablo franchise."

[Source: Blizzard]

Our Take
While the job listing seems clearly for Diablo, whether that means a new game or another expansion is unknown.