Player housing
More moogles
Less grindy grind via more low-end content
Less powerleveling
Mail System
Map redesign
Some form of skillchains
Some form of level sync
More/different mage classes
Someday, Linkshell airships would be cool
World bosses like the dragons in XI, but with quicker respawns
Ninja and Samurai classes
A pet class
I'd like to see crafting become less tedious


There's more but that's all I could think of right now.