Looking over the class/race combo there are quite a few which should exist and be playable.
Alliance:
Human Shaman: No reason not to have regular humans as shamans anymore, our Kul Tiran buddies can teach us how, we have seen human twilight shamans as well. So no reason not to have Human Shamans.
Night Elf Paladins: We have seen one Nelf priest become a paladin in Legion and like with Tauren being able to be Paladins we should have Nefls be able to be Paladins as well.
Gnome Shamans: I mean we have Goblin Shamans⌠so why not? Have gnomish mechanical totems. Gnomish engineering IS better after all.
Void Elf Shamans: Like with twilights hammer we have seen void corrupted shamans in WoW before so we should have the race filled to the brim with void be able to be Shamans as well. Plus they can 1UP their blood elf brethren since Belfs can be Pallies and Void Elfs canât.
Kul Tiran Paladins: I mean its not unreasonable for them to be paladins, they are just chunkier humans after all.
Horde:
Tauren/Highmountain Tauren Mages: Literally the only 2 races that cannot be mages as of right now. Arcane Magic isnât that complex for them, I mean undead only need half a brain to use it.
Highmountain Tauren Priest AND Paladins: There has been enough intermingling with their fellow Tauren brethren for them to learn the way of worshiping the Sun to be Paladins and become Priests.
Overall horde side has it more together for race/class comboâs.