I feel like they aren't gonna remove the Limited Job idea, buy I do think there are a few things they can do to make it more viable.

  1. The first disparity would be the Weapon, there are only 3 BLU canes in the entire game and I think it wouldn't be unreasonable to use a few BLM and WHM weapon models to fill the gaps, though with that said BLU weapons are the most similar to any other weapon type in the game right now apart from the only jobs that share a base class, so there needs to be some distinguishing in most cases, if only in lore.
  2. I would propose a bare minimum, Letting them queve for POTD/HoH and Command Missions. And in the latter case, allowing BLU to learn spells from the mobs there (followed by tweaking the mobs to that they can have all the spells, this comes at the cost of making them specific to the save file). For command missions, it should be obvious, you're going with your squadron, each of them have nonstandard abilities themselves so balance shouldn't be as much of an issue.
  3. Regarding the DF, I don't think they ever plan on changing those,nor do I think they are gonna do the following given their opinion the Book Jobs (SMN/SCH). But the easiest method would be to have similar split for three roles, (Healer, Tank, Magic DPS), and then require certain spells to do specific instances and roulettes.