No it won't be enough. People think they want D2 like it was but they actually don't, simply because they're used to new stuff in games that is now standard and if you take it out, likely will pan out to be an inferior experience.
I don't get the comparison with WoW, LoL, Fortnite, etc. All different genres that have nothing to do with Diablo (maybe WoW for some aspects). Until you're referring to twitch views that are the shittiest parameter to define if a game is good or not.
I want D4 to be more D2 than D3 for sure. However it needs to bring something new to the table to distinguish himself from the other games around, PoE first of all but also underdogs like Grim Dawn, the new Torchlight Frontiers, etc. The ARPG genre is in great turmoil with many different stuff that have come out or are coming - so they need to make a NEW game. It needs to still be a Diablo game, but a new one.