The statement was made by Piepiora in the twitter when answering a fan about it. This confirms that anyone who wants to reach the maximum level in Diablo IV will need to spend an exorbitant amount of time in the game.
Days ago, Blizzard also said that it would take around 80 hours to complete each season battle pass, which includes both free and paid cosmetic rewards.
A new beta for Diablo IV will take place between May 12th and May 14th, this being the last chance players have to try the game before launch. This beta, as explained by Blizzard, aims to stress the servers to the maximum.
Diablo IV arrives June 6 for PS5, Xbox Series, PS4, Xbox One, and PC (Battle.net).