One thing that would probably single handedly revive campaign would be new AN gear that is for lv90+.
Wouldn't have to be much either, just a handful of items for each nation, with prices ranging from 200-500k AN, and let the gear be at the same power level as NNI gear, just in different equipment slots. Grips, ammo, earrings, rings, belts, neck pieces and capes, yes please.
For example, there is a 1 (10 in campaign) hMP grip available from AN in windurst for something like lv75 or less. What if there was a a lv95 grip with 20 hMP, and latent effect Refresh (active while not engaged and not /healing)? Doesn't sound too overpowered to me. Basically, it would let you idle in earth/terra staff instead of owleyes while still refreshing, and just not have to bother with that annoying +10% damage taken. I know I would save up for this even if it cost me 600k AN.
For the melees, what if there was a grip with even more sTP than rose strap? Let's say... 6 (+30 in campaign!) sTP, 5% Conserve TP, +1% attack. Sounds pretty sweet to me.