An Aether-based necromancer seems quite likely. Probably with some kind of acid/poison/vitality skills to back it up.
Also possible is a direct damage mastery built around Chaos. We have the Occultist, but it has virtually no Chaos-AOE (I'm not counting the 5m Sigil or the 2m Doom Bolt) or ranged damage spell (if you don't use the Arcanist's AR). Could be interesting with, say, some kind of short range teleportation skill (void-jump?).
Maybe a mid-range phys/piercing melee combatant? Might be nice to have an alternative to Soldier/Shaman or Soldier/Nightblade, which are Phys-Internal/Phys-Bleeding and Phys-Internal/Piercing-Cold, respectively. Could be squishier but have piercing-based AOEs.
A dual-ranged specialist (ala the dual-melee Nightblade) could also work well, with a twist (acid/vitality/aether/whatever).
Some kind of aura-monk? A second support class like the Occultist would be useful. It might specialise in internal trauma and vitality.
Finally, a class built around immobile constructs could be handy. Like the Shaman's totems, but more versatile.