I think FFXIV has a set of solvable issues with a priority list, and I expect a lot of player requests will be granted, especially cosmetic requests (like expanding the glamour system for instance, or revamping inventory space systems).

My main focus would be gameplay oriented. The big thing missing in FFXIV is more endgame content in between normal and savage, and in light party. Sure there are Deep Dungeons and treasure maps, but I think having harder endgame dungeons bringing gear between normal mode and savage raid ilevel would be great. Or even more cosmetic rewards. They could even use the Unreal scaling system (without too much gear synch) and have something close to WoW's mythic dungeons.
This could also bring a bit more customization in jobs between various types of content in terms of stats and rotations.