According to the store page, August 31st, 2021.
I was excited for Diablo 2 Remaster but.... this wins, pre-ordering now <3
I hope that goes well for you. I never pre-order anything anymore, as it seems like there's about a 50% chance of the game turning out to be a complete disaster. I always wait a couple weeks to make sure it's getting positive reviews before I commit. I'm excited about Diablo 2 as well, but was very glad I didn't pre-order Warcraft III Reforged, for example...