Could an indication of a playable dragonkin race be the Shadowlands update to the Dreadlords models from 9.1? They made them dimorphic like a playable race (unless I am forgetting previous female Dreadlords). Seems like a decent chunk of work for only 9.1 and 9.2.
What I mean is essentially throw the Dragonid/Dragonkin model on the Dreadlord skeleton and utilise the animations already produced etc.