Well at first Glance... Summoner will likely be Nerfed into the ground for anything but the MSQ content.
BUT....

BLM as it is right now won't lose much. Fire II only loses 20 potency.... but you gain 30 Potency from Thunder II which is now AoE... and Procs on top of that. So... well... nothing was lost at all and the overall AoE Damage for BLMs will see an overall increase likely... Thunder IV is also AoE and procs too at a 50 potency.

Obviously we don't know whether it procs AoE, but likely it will since it is an AoE. And like all BLM procs will proc the Full damage all at once.

You do lose a whopping (sarcasm) 20 potency off Fire IV... which was 280 now is 260... so not much of a change because Enochian is now always on so you're no longer limited to doing it only in Enochian.

So basically you can now Fire IV for however much you want to then switch to the Blizard magic to instantly restore all your MP and then go again.

Between the Thunder AoE and Procs... nothing is lost on the Fire II nerf.

Summoner loses some massive AoE... BANE is pretty much nerfed into the ground, and they lost Bliz 2 and Miasma 2 on top of it. And they also took a hit to Ruin 3 with a 25% DPS loss as well as a 40 potency per tick loss... to their DoTs. So this job likely will not be able to compete at this point...

Red Mage is a different story... this one will be dual casting 200+ potency nukes, so its DPS in single target will be incredibly high. But this one lacks any real clear AoEs so will be limited to Single Target only.

From what i can see Red Mage may turn out to be slightly higher in Single Target. Black Mage will have Strong Single Target and Top rated AoEs... Summoner will lag behind both.