Possibly the Hasharii from Harad, unless Nazgul wants Rhun to also have a commander unit.
so what is going to be the evil-men equivalent of black uruks or fountain guard i.e. limited unit count, but very powerful?
Jes' give him time, patience...
and there is a hill troll in the rhun forge and orcs in the harad slave mill... are those going to be reskinned?
Maybe the Axemen could be helmet-less and have brown clothes rather than purple-ish, and the wainriders could have trench-coat-like robes like GW's Dragon Knights have...
and i think that there could be slight differences in armor or clothing (like in total war) between easterling units, because there will be 7 units (swordsmen, spearmen, pikemen, archers, kataphracts, wainriders, axemen) with pretty much exactly the same skin, and even gondor and isengard aren't that uniform. there should at least be some variation.
Those sound like what's happening, Naz???