Kurgans might be a pipe dream, but I still think it is possible to pull off and for this topic I will give a unit rundown list to demonstrate it isn't impossible to make an army list of these guys.
-Standard Kurgan (ax and shield, sometimes mace or great ax)
-Kurgan Drummer (twin hammers)
-Kurgan Woman (twin swords)
-Hulking Warrior (chained sickle)
-Flayerkin (bladed arm)
-Standard Hung (ax and large ax users)
-Standard Horseman (ax and shield)
-Chimera (neither WoC or Norsca have them)
-Mutalith Vortex Beast (also used by neither)
-Skin Wolf (regular and armored)
-Mammoth (feral, war, and war shrine)
-Tong (spiked hammer users, berserker units)
-Hung Hunting Dog
-Hung Dog Chariot
For this list I did have to get a little creative since I could not find Kurgan models, but I did spot a lot of artwork. These guys could play the same as Norsca in that its mostly tribesmen commanding monsters. I was not able to find any information on ranged weaponry so I figured why not have this a pure close quarters faction (minus magic users)? I did add the Hung and their dogs since they had too little to go by on their own and since both tribes are in the Eastern Steppes it'd be easy to amalgamate them together. Skin Wolves, Mammoths, Shamans, and Chieftans would carry over easily from Norsca since there is lore of them in that region as part of Kurgan forces (I was tempted to include Stone Trolls and Ogre beasts, but to the best of my knowledge those never sided with Chaos). Since Chimeras and Mutalith Vortex Beasts are not in the WoC or Norsca roster I figured they would be a good fit to make them a bit more distinct. Chaos Ogres I included since it would make sense given their geography. Tong are technically their own tribe, but could function as monstrous infantry. If CA makes weapon and shielded variations they could make 11 on infantry, 2 on cavalry, 10 on monsters, 1 on chariots, 2 on heroes (more depending on shaman lore), and 1 on Lords giving a total of 27. Keep in mind this is if CA decides not to include missile infantry and cavalry from Norsca and make them more Kurgan flavored. Slaughterbrutes I left out because they are more or less only tamable by chaos warriors with the necessary armor and weapons.