Bottom line: The last major Diablo game came more than six years ago and a lot has changed since that time. At this point, it seems like nothing short of a Diablo IV announcement will be able to rescue Blizzard from its PR nightmare and that might be exactly what we are in store for.
Blizzard has been on a bit of a rollercoaster lately. Most expected the company to announce Diablo IV at last year's BlizzCon convention in Anaheim. Instead, gamers got a reveal for a mobile version of Diablo that still hasn't launched and people weren't happy.
The developer's fortunes took a turn for the better this summer with the arrival of World of Warcraft Classic yet inexplicably, Blizzard somehow got itself tangled up in the ongoing protests in Hong Kong. Public opinion took another ding. With BlizzCon 2019 just around the corner, can the embattled developer once again redeem itself?
Rock Paper Shotgun points to an article from German publication GameStar highlighting an upcoming Diablo art book. An official advertisement for The Art of Diablo specifically mentions the publication will include artwork from Diablo, Diablo II, Diablo III and Diablo IV. Notably, Blizzard has never officially mentioned a game called Diablo IV and a typo seems unlikely as all three of the other games in the series are referenced individually.
BlizzCon 2019 runs from November 1-2 although pre-game festivities start a day earlier on Halloween. The Art of Diablo is due out in early November.