For me, after being scorned by the mess that is D3; I expect at least the following before I’m willing to drop money on it:
At least 8 players per game with custom game names with configurable options; including game name, optional password, and player limit. There should also be game listings where the creators chose game names.
Dueling anywhere outside of town with optional loot toggles
Trading with no soulbound garbage
Diablo 1, Diablo 2, or Path of Exile dark theme of visuals, sounds, and level of maturity. D3 is currently themed like the bad guys from the Power Rangers (the old show, not the movie.)
For me personally, those are my 4 critical requirements before im willing to drop money on D4.
Meaningful choices, no endless expgrind and Pvpve of some sort. Trying to steer away from the direction D3 went with most design choices would be preferable.
The hostile system gave Diablo 2’s pvp a bad reputation. It’s a major reason why most pvers are strongly against pvp returning in any shape or form. So don’t bring back the hostile system; have pvp require the consent of all parties before they can engage one another.
I think I’ll wait for months before I make any move on buying any new games. Even BL3 couldn’t budge me and I doubt a potential “D4 battle royale lootershooter- ARPG edition” could make me pre-order anything.
D2 lacked an infinite scaling difficulty, it used its PK threat as a last challenge. Unfair? Nobody said it would be fair. While it can be tweaked somewhat I believe it added some depth to the game.
If it’s a good game I’ll buy it at full retail if not then no I won’t.
I don’t have an itemized litmus test, it won’t be difficult to tell if it’s good or not either.