They could also make it so BLM has access to all of CON's nukes without any downside, and give THM Profundity. It's already been stated that PLD requires that you have both GLA to 30 and MRD to 15. You will likely need THM to 30 and CON to 15 for BLM. That would give you all the nuke spells you need. And more than likely, BLM will be getting some of its own magic potency+ abilities that blow anything CON could to do out of the water.

They may not need to switch abilities around all that much. But I do see a Buff coming for THM's nuking ability.

I can't wait for the notes on ability relocations for thaumaturge and conjurer so we can stop arguing about what class is what job and start arguing about what job gets what spells.
We already know what class gets what job. Some people are just really angry because they guessed wrong.