Then there won't be a Dungeon, how could there be one in Heroes?
apparently, there can be) but they won't remove the Elves either, and Mages are also useful guys... but the Dungeon is just okay, it's not like in Heroes I-IV, where the Dungeon was really important)
and in general, I'm making assumptions based on the lore. In Heroes V, the Dungeon was replaced by the Elves. And they appeared sometime there) maybe in Heroes VI, it will be a time when the Elves didn't exist yet, so there won't be a Dungeon either. And that means there will be Mages who summoned beastmen to replace the Orcs. Maybe the Mages will be more evil... who knows
Added 2 minutes ago
although I haven't read the lore of Heroes V and I don't know when what happened there)
but in my opinion, Mages and Elves are better than the Dungeon.