I think someone pretty much touched on all the things I'd like to see.
1) Newer Ranks/ Tier 3 & 4 FC buffs available
2) Expansion of FC Chest
3) A Board or something that players both old and new can click on to find a FC to their liking. (Gridania has a perfect spot for it at their GC HQ) (Also XI did this like 2-3 years ago, so why is XIV behind?)

*On a sidenote the issue with FC only content is that there'll always be that handful of crybabies that will whine if they can't partake in it because they either a) don't have a FC or b) choose not to socialize within the game.