Idk whether this can be done or not but i suggest you to add mounts like Tyreal's Charger, Korkron Anihilator or Alliance Lion to Wotlk store. This would be a nice tie to the expansion that is soon to be canceled and them mounts being a cosmetic feature only wouldn't impact gameplay in any way.
Make them coins only if you wish and idk slam 100 coins or so for their price.
As it is none of the mount models have been updated so I don't see it happening that they'd add ones from a different game. You can get a custom patch that changes their model to newer ones though