The core of BLM is trying to cast as many FireIVs as you can while still casting Fire to maintain AF/Enochian, so I think any BLM overhaul needs to give the relevant skills as early as possible rather than at level 60.

For instance, Convert could be a thaumaturge skill, while BLM learns Enochian at level 30 and FireIV at level 35. (Maybe just call it "Void Fire" or something and give it lower Potency which grows at level 60 thanks to a trait). That way BLM players are learning to balance their high power, high risk spellcasts against low power, low risk spellcasts for most of their careers rather than only at the end of the first expansion.