I would personally like to see a talent tree system specific to FFXIV. This way you could have a ninja for example that can sepcialize in Ninjutsu's for added effects (DPS oriented). Or they can specialize in stealth talents that would make Hide more useful than it currently is (Stealth oriented). Or as a third option they can specialize in finding more weakness in enemies to use more trick attack like de-buffs and other de-buffs (support oriented).

This suggestion would require a rework to the current combat system, so it most likely will not be very well liked. However, it would allow more variety in play styles and allow people to try out different builds to help with burn out and stagnation.