Next healer class released should be

[Seraphor]

Your approach is strictly gameplay based
But you can't make FFXIV jobs without lore, how would you pass a chemist as a DoM job from Garlemald by Garleans (who don't use magic)?
If Chemist gets added it'll have to be a DoW. I don't see how they can get around the lore.

MCH is a Garlean-adapted job.
Garleans use the technology to convert Ceruleum into magically-augmented shots.
The WoL uses the same technology with their own aether instead of Ceruleum.

GNB is the same.

Chemist would be no different.
Instead of Ceruleum you use your own aether, thus it's a DoM.