In my opinion, it's not that big of a deal as I'm sure that the Huns will be playable in custom/MP battles like the Mongols and Timurids were in M2TW. The Huns never established a well ordered political state anyway. They came in, kicked ass, scared the spit out of everyone, then disappeared as quickly as they came.
My main hope is that the Hunnic Confederacy will be depicted correctly. They were far more than elite cavalry/horse archers as they also incorporated the Sarmatians, Gepids, Goths, etc into their confederacy.