https://www.cnet.com/news/diablo-immortal-brings-blizzards-dungeon-crawler-to-mobile/

Specifically, Blizzard said Diablo Immortal would featuer large, "shared outdoor zones" where players could explore the overworld and encounter other players online. If you meet a friend in that overworld, you'll be able to invite them to an instanced dungeon for a more traditional Diablo experience.

And Blizzard stresses that this is a traditional "fully-fledged" Diablo experience, complete with six traditional classes, challenging boss fights and deep gameplay. And, true enough, the on-stage announcement showed off Barbarian, Crusader, Demon Hunter, Necormancer, Wizard and Monk classes. It also says the game has an active place in Diablo lore, taking place in the lull of time between Diablo 2 and Diablo 3.