According to the unofficial information yesterday, Blizzard officially announced today Diablo 3 for the switch. Unfortunately, Blizzard has been silent about a release date so far and only gives "this year" as the time frame.
There is a video with game scenes and a first picture of the bonus items for this Diablo III Eternal Collection. There is also an extra homepage for them Switch version.
Exclusively for Nintendo Switch ™
Discover elements from Zelda's world in Sanctuary. The Eternal Collection for Nintendo Switch ™ includes Cucco as a companion, a Triforce portrait frame and an exclusive transmogrification set with which your heroes can wear Ganondorf's imposing phantom armor. There are also unique decorative wings. (Source: Blizzard)
Here is the message from the Diablo 3 team:
Diablo 3 for the Switch
The minions of Hell have grown incredibly strong since Diablo III was released. Fortunately for the high heavens, reinforcements are already on the way.
Later this year, Nintendo Switch® players around the world will join forces with the Diablo III: Eternal Collection ™ to use the power of their portable console to destroy demons and claim mountains of loot anytime, anywhere.
Later this year, Nintendo Switch® players around the world will join forces with the Diablo III: Eternal Collection ™ to use the power of their portable console to destroy demons and claim mountains of loot anytime, anywhere.