The problem is not using dragons, is HOW you use then, many franchises succeed in doing it, But i doubt wow will, because Danuser is not a good writer for the main plot, he will fuck thing sup with his fanfic just like he did in shadowlands, but now there is no one else for him to blame.
Dracthyr and evoker are blatantly copy of Demon hunter, they just changed tank for healer, ranged dps from melee and are selling the class as new race. Hell even the "race" itself is a worse version of the dragonkin we had like drakonid