Blizzard should have just done it like Bethesda did for Fallout 4:
"Here is a teaser for the upcoming next game in the series, and to kill the time until that releases here is a mobile game."
But noooo, they didn't mention anything about a new game. In fact after hyping up the community a few months ago stating "We have multiple Diablo projects in the works", they then backpedaled a days before Blizzcon and said fans should temper their expectations. They could have at least teased something. Fans love teaser no matter how short they are. Loot at TES VI, MP4, Animal Crossing.
It is just baffeling how bad this was handeled by Blizzard, a company which prided themselves for beeing in touch with their fanbase.
Oh how the mighty have fallen.