Following Blizzard’s Diablo: Immortal announcement from BlizzCon 2018, which led to an immediate negative response by fans, Kotaku reports that Blizzard’s original plan was to release a tease for Diablo 4 at the end of their announcement.
However, the plans to tease Diablo 4 were reportedly pulled last minute.
According to Kotaku, two people familiar with Blizzard’s plans said after the announcement of Diablo: Immortal, a video was going to pop up in which co-founder Allen Adham would tell the audience that Diablo 4 was in development.
Source: IGN.com Diablo 4 Announcement Reportedly Pulled From BlizzCon 2018