I'd be fine with story mode raids being solo instances or tank and spanks with no gear. Though of course in the latter case SE would have to stick it in a tome roulette or something to keep queues alive. I also like the idea of more interaction with the story npcs in those instances (as as aside I really like the instances we got with mini npc parties in Heavensward).

I'd also be okay with waiting for nerfs and echo on the condition that SE actually adjusted every fight.
The problem with Coil was they left certain fights as walls with a ton of PUG unfriendly instant wipe mechanics with t5 and t9 causing the most problems. I can't speak for the difficulty of Final Coil since I never reached it synced but if I remember right very few adjustments were made to it overall.

I liked what SE did with Brute Justice in A8 in giving the Savage version an extra phase not seen in normal. I think gameplay focused bonuses for harder modes like that are great and hopefully not too expensive for SE to create.