I'm not sure what I want actually.
Initially Diablo 3 was made to be an MMO, but that was scrapped for reasons I can't remember anymore, and the development was taken over by Blizzard self, instead of Blizzard North (D1, D2 & D2 LoD creator). So World of Diablo WOULD have been nice, but with my personal experiences in MMO's, then the MMO genre can get both of my middle fingers. I love MMO's, I just hate and love that you have to work together to achieve end game content, and people SAY they wanna be serious about it, but puts zero effort or work into it.
I don't think it's gonna be a D3 expansion or character DLC or anything like this, since PoE is so huge at this point in the ARPG genre, that it would make sense for Blizzard to keep going on that.
I don't think it's gonna be a Dark Souls type of game either, based on the games Blizzard has right now, they haven't made that type of game, or at least not what I know of.
So I'm gonna say D4, whatever type of game that might be, and it's gonna continue the story, so I don't think it's gonna be a prequel, but a sequel. Since the books kinda makes up for the holes in the story between the games
This my friend, my words. Amen