I think Dark Knight will be an Au Ra unique class for a few specific reasons:
In other word's, Dark Knight might get race locked like Dragoon. xD
This is just a theory though. I dont know if this will actually happen, but I did do alot of thinking on the matter.
- Ishgard is pretty "Hollier than thou" country or state, so it's unlikely they would work or even remotely think of using Dark Magic.
- Ishgardians are getting Astroligian hand's down because they have an astro lab.
- Machinist look's like it will be associated with Cid and his Ironwork's company. I expect Cid to be the teacher since he is a mechanic/uses machines.
- The dev's will at least make ONE of the classes have an Au Ra instructor.
In other word's, Dark Knight might get race locked like Dragoon. xD
This is just a theory though. I dont know if this will actually happen, but I did do alot of thinking on the matter.