It seems unlikely to me that Demon Hunters would be the Hero class of Hunters. In WC3, they were melee combatants, most definitely not ranged attackers.
Just because "Hunter" in in their name doesn't mean they're the hero version of the Hunter class. I think Demon Hunter is more likely to be the hero class of Warrior or Rogue.
Same with Shadow Hunter for trolls. It's more likely Shadow Hunter will be the hero version of Shaman for trolls.