I’d like to see these heroes in the game, I like to make the topic to motivate dear developers to make more heroes in a year, although they are my favorite too.
Spell Breaker
Naga Guard Harpooner
Crypt Fiend
Hogger the Gnoll King
It seems it is impossible though but I have big hope and would love to play with them in game, hope to see the best in the game.
Izual, Andariel and Lilith (both looks similar according to Diablo 2 so and could be used as nice skin for Kerrigan), Duriel (can be skin for Anubarak), Zoltun Khule, Cydea (can be good skin for Zagara), Ghorm (can be good skin for Stitches), Inarius, Ancients (can be good skin for TLV), Lister the tormentor and many, many more. Actually it is discussion matter that Diablo characters could outgrow Warcraft characters in number as Diablo has tons of important characters.
I Mention on Hero more than skin,though actually they can be hero too.
And comparing Diablo and Warcraft,Warcraft is the main because its the main in Blizzard and sure Diablo has big right, but we can see more than of warcraft heroes too.
Imagine the Crypt Fiend near her too, wanna accept it?