Square Enix has announced that Final Fantasy XIV world will be merging on March 27th. The server count will go from the current eighteen to ten. All players will be required to choose which server they would like to live once the merger is complete.
From March 1st through March 19th, players will choose which server to have their characters reassigned. According to the dev team, the merger is "intended to improve the player experience during the period up to the launch of FFXIV Version 2.0."
Read more of the details of the merger on the Final Fantasy XIV site.