When it's finally stabilized of course...
Three words "Bring back Vana'diel"
Before you roll your eyes please give me a moment of your time and read on.
The lore for Eorzea hasn't fully been established, there are always talks of the main land. So why couldn't the main land be Vana'diel? I'm not talking about Final Fantasy XI's Vana'diel but in fact Vana'diel several hundred years after Final Fantasy XI.
We already have what looks to be evolved races of the original's in FFXIV so here is my idea.
A major disaster happen long ago that is now only remembered by few who still study the histories of the past. The once proud races of Vana'diel forced out of their home lands retreated from a losing battle and struggling to survive. The once proud races lost their heritage and evolved to their new homes, taking on new names and rebuilding their heritage from scratch. The past was forgotten and a new future born.
There could be an epic story involving rediscovering Vana'diel and learning what happened in the past for the calamity that struck long ago has returned to finish what was started. A brave few sacrificed their lives to buy the world time, time that was lost. Now it will be up to the new adventurers to discover the tragedies of past to protect the future.
Discover the once thriving city on the sea Jeuno now in ruins occupied by beastmen. San'doria once the proud city of the elves now cursed by a plague of death as the ghosts of the fallen roam the streets in misery. Windurst and the lands of Saruta Baruta now a lush thick forest over run by creatures which would also be the home of ancients that know the echoes of the past. Bastok the last city to fall crumbled in to the sea, now a slum where dirty dealings and corruption can be found. Selbina, Mhaura and Kazham cities by the sea where the races flooded to escape and make their stand but eventually ran to Eorzea once discovered to retreat the main land in hopes of new lives. Norg is still the home of pirates of course.
The entire world of Vana'diel changed in fact only the ancients still call the land Vana'diel. I dare not try and think of what it would be called and all the area's are called different names for the original names all were lost in time. Those who sacrificed their lives bought time for the people of Vana'diel to escape to the sea. This was just my idea I'd love to rediscover Vana'diel in a new light.
I could see this expansion being released along with the PS3 or PS4 version to bring people who played FFXI and others in to the world as well as the veterans who left FFXIV or who are still around like me supporting Square 100%!!
I am also interested to hear what others have to say of my idea!! even the devs!!! also bring back Naoshi Mizuta it would only be fitting that he bring new breath to the ravaged lands he once brought life in to.