It has finally been announced at the Game of the year awards.
To keep it simple and short, here you go.
The tentative release date for Diablo 4 is 6/6/23 ( Yep 666 )
Please take a look at the new trailer! It is one of the coolest trailers i have seen from blizzard in a very long time.
https://www.youtube.com/watch?v=KsNDMHvz98M
The pre orders are also available now. there is NO physical box until the 15th for pre order. but the physical box does NOT include a game code and cost around $97 USD