Blue's News has the lowdown on an unpaid internship at Blizzard that seems to hint at a new Overwatch project.
This is for a Generalist Art Intern, however, not a paid position, so it seems an odd starting point for a AAA developer and franchise. But they do say this is for an "unannounced project at Blizzard" and under recommended talents they list "Knowledge and understanding of the Overwatch universe" as a plus, so there's that.