There's a few others doing high content with Disc Priest and I think potentially a Warlock or Mage. (Mage right now is insane DPS if you have the right gear). I just watched a +28 run where the Mage did 225k DPS average for the entire dungeon run, on short burst windows it was over 300k.

Ele Sham is in a bit of a pickle - I really want it to work but it's main form of AoE which is earthquake is a targeted. I did a few test runs with 1 tank / 4x Ele Sham and they just didn't pump the DPS like a Druid could. They would work but it felt less effective. The Druid was also able to heal up the team passively and actively, and while the DPS was lower could still dps while moving.

They are getting buffed for Shadowlands but that targeted aoe is a huge downfall. Comparatively Starfall is the same issue but has a much larger radius. The benefit is that Starfall is being changed in Shadowlands to be an AoE around the caster that moves with you and also refreshes your dots. So it's going to be an insanely good mechanic, and even for Farming.