It doesn't have to be so IMO. If they added a Dragonsworn (whatever the name) class and it followed your suggestions, this could work as :
- Tank spec = Black dragonflight follower
- Healing spec = Emerald/Ruby dragonflight follower
- Ranged DPS = Bronze/Azure dragonflight follower
In this case, only the tank spec would be a melee obviously and it could fit the fantasy of a Dragon Knight wearing 2H weapons (polearm/2H mace/etc.). I think dragons themselves are mostly casters when they are in human form except for Deathwing which wore a 2H Mace and thus would have been a melee.
TBF Chronomancer or Timewalker are really close and one could just be a spec of the other if a "Time" class was added![]()