Fire II is the same as before, 100 potency - Ley lines lets you actually cast Thunder III in ice -> fire transition so you get 6 more seconds out of that buff. Sharpcast can be used to max dmg while buffed with dmg+ for extra dmg and prolonging the time you stay in fire. Judging that mobs die usually in one firechain up to lvl 56 i wouldnt say they nerfed it :P Blizzard IV is a 280 potency which you get at 58 and Fire IV at 60, will have to see how playing changes when those two hit.

tl,dr:

BLM is more technical then before. Our Single target dmg got buffed and at 60 with Fire IV we will dish out really big hits. Aoe got toned down, but im fine with that - AoEing in dungeons is still fast thanks to the buffs we got

('-')/