Diablo Immortal
I figure an entirely new news post for this would be appropriate. Yesterday, it was reported from Kotaku's Jason Schreier that Blizzard had apparently pulled a Diablo 4 announcement at the last minute from BlizzCon 2018.

A video had apparently been recorded featuring Blizzard's co-founder Allen Adham talking to fans about a new Diablo project. The original statement says that Blizzard pulled this video announcement from BlizzCon 2018 at the last minute. Blizzard has since come forward to make a public statement about this, saying that no, this wasn't the case at all.
“First off we want to mention that we definitely hear our community. We generally don’t comment on rumors or speculation, but we can say that we didn’t pull any announcements from BlizzCon this year or have plans for other announcements. We do continue to have different teams working on multiple unannounced Diablo projects, and we look forward to announcing when the time is right.”

What isn't up for debate, however, is the fact that a video exists. The only thing that has been disputed from Blizzard is that the video was meant for or pulled from BlizzCon 2018.

Kotaku goes on to say that they can confirm that Diablo 4 is in development. They also share that Diablo 4 has "changed drastically over the past four years and may continue to change further." Schreier notes that there are at least two different iterations Diablo 4 that have been worked on under different directors.

So there we have it: Diablo 4 is in development, though this should have been obvious by Blizzard's initial comments back in October. Kotaku's initial sources got a few details wrong, but that's why corrections exist. There is a video that was recorded, but it apparently wasn't for BlizzCon as initially suggested. Diablo Immortal still very much exists and is coming to mobile devices at some point. Diablo fanatics will still be absurdly mad as hell and on the verge of flipping virtual cars.

And the world keeps spinning.