Is Diablo 4 in the works? Blizzard’s careers page certainly seems to suggest so- the company appears to now be hiring for a brand new game set in the Diablo universe. The game seems to be a 3D title, and it is early in development- these suggest that it may be a brand new AAA title, rather than a spin off or an expansion. Diablo 4 seems to be likely, given all that.
Of course, whatever it is, knowing Blizzard, it will take a few (read: a lot) of years before it is actually ready. And with Diablo 3 doing really well still, it’s likely Blizzard may look into supporting that for a while, instead of making a new game right away. So while Diablo 4 may definitely be in the works, it still may be a ways off.
Diablo 3 is currently out for the PlayStation 3, PlayStation 4, Xbox 360, Xbox One, and PCs running Windows and Mac. Having sold over 30 million units worldwide, it is the most successful entry in the Diablo series.