Kabooa hit the nail on the head.

They will not uproot current framework on new jobs. When RDM and BLU hit I am fairly certain, many will be sorely disappointed. BLU for instance, will learn an ability every 5 levels just like any other job and will start at level 30 (this precedent was set with DRK/MCH/AST). There will be no "learning" boss or mob abilities as it would not fit the mold that the game operates under, there will just be thematic skills learned every time you complete your job quest, as with any other job in the game.

Lastly, devs already said they made a mistake with ACN by sharing a DPS and HLR on the same root class, which they will not be doing again due to balance issues.