Another suggestion from me, something that would be just for fun without any other use: the possibility to get an airship to travel the world. This airship would be a complete different thing from the FC airship system.
This personal airship's function would serve as an alternative for Aetherytes (that's why I said it would be just for fun). On land, we would use the "Airship" action similar to how we use "Return" or "Teleport" to travel to another place of the world.
However, while "Return" or "Teleport" takes us to the desired destination at instant, "Airship" won't. When using "Airship" we will appear in a detailed but miniaturized version of the world, similar to the classic Final Fantasy overworld maps. There, we can control our airship manually to go to the desired location, just like the airships in the classic overworld maps.
As I said, It would be just for fun since its use would be actually the same as the "Return" and "Aetheryte" actions, but non-instant. Obviously, I know this would be complicated since the center of the world map is not worked (Ilsabard), maybe it would be also hidden by clouds and would be updated through patches when new zones are revealed (though depending of the progression of the player, those will be unaccesible).
Also, this FFXIV world map could be the scenario for an special high-difficult FATE similar to the Mhachi instance thing from Diadem. A rift would open at some occasions and people would enter into an special instanced FATE.
So my idea would be similar to this (ignore the enemies and shots thing from the video).
https://youtu.be/E3Y8un26RYI?t=160