I think I'd much rather if jobs just got to have a dual role they can queue for with the flip of a button. Let that Dragoon feel vindicated when they turn on their stance, let that White Mage remind the Black Mages why there was a War of the Magi, let that Warrior shake is green heart out.

We already know it's possible for skills to have alternate functions/effects via PVP, and Duty Support/Trust NPCs have been double-dipping for years. Maybe instead of ever upwards advancement we just do some side-stepping.