[Dev idea/request/suggestion] GCNM Grand Company Notorious Monsters (spending seals)

I would like to see some sort of Grand Company Seal exchange for a unique battle entry item to obtain,unique loot,tombstones, from a specialized instance.
The one thing that I miss most about FFXI is the BCNM/KSNM challenge of not only the extreme difficulty of some of the fights but the excitement and at times agony:p of getting an item to drop from the chest. I would love to see unique instanced fights in a similar manner, is this something that would be possible within FFXIV?