Doubt necro ever happens with the WD.
Honestly all D2 classes are covered already.
Barb > obvious
Amazon/Assassin > DH
Wizard > obvious
Paladin > monk
Necromancer > WD
Leaves druid, and don't be surprised if a shapeshifting class exists in the future, I wouldn't be. Considering druids are the brothers of the barbarians, I wouldn't be surprised if they were literally re-added to the game as they were, just like the barbarian was.