In case you missed it, Blizzard announcements at the BlizzCon 2018 have been filling news post for quite some time, and the one that took a lot of flak is the mobile Diablo Immortal title.
According to Kotaku, Blizzard actually planned a Diablo 4 announcement as the keynote finish but it was pulled at the last minute. Citing two sources "familiar with Blizzard's plans", the report says that there was a video in which Allen Adham, Blizzard co-founder, talked about a new Diablo project, pretty much confirming its development. Diablo 4 development was already teased earlier in an official blog post from Blizzard.
The community has been on a wild rampage regarding Diablo Immortal, but the company is betting that the game will be a big hit and some gaming sites had nothing but praise regarding the demo.
Hopefully, Blizzard will soon announce Diablo 4 as well but until then, we can look forward to other titles announced at the BlizzCon 2018, including the Warcraft 3: Reforged.