You know, I admit I kinda want them to add Decay as a magic type we could use. Perhaps as some dark form of a shaman or druid. We’ve seen with them adding Augmentation Evoker that they seem to know how to add a spec to an existing class (though I do understand it is likely they had been working on this before or after Evoker was added), but I still would be interested if they added in a Decay-focused specialization to a pre-existing class.
I’m just saying this cause, it seems they are just forgoing any logic anyways with classes by letting races be things they, lore-wise, wouldn’t (like night elves and lightforged draenei being warlocks despite having suffered at the Legion’s hands and waging war on them). So, why not just add in something with this magic that you introduced with Dragonflight?