Just like tinker and alchemists could be under one class (tinker = ranged DPS, alchemist = healer, steamwarrior = tank), I think that, with some creativity, one could fuse Dark Ranger, Shadow Hunter and Warden into a single mail-using, shadow-casting, weapon-using class. Shadow Hunter could be the healing spec, Warden could be the tanking spec and Dark Ranger the ranged DPS spec.
I know originally Shadow Hunters are trolls, Wardens are night elves and Dark Rangers are Forsaken, but for gameplay purposes you could say that the class represents just the concept of a wapon fighter that employs shadowy magic (so "shadow hunter" uses melee weapon + off-hand, casts wards and voodoo-like spells; "warden" goes into melee, blinks, summons spirits of vengeance; "dark ranger" uses ranged weapons, summons dark minions)