The Mist may still remain, its mentioned that the region of FFT is split from the eastern side of the continent (Rozzaria and the Galtean Peninsula) by a Jagd. Which is a Mist filled area. I still hold to the theory that the Mist is also the Dark from Vagrant Story, seeing how they have similar properties (use for summoning, magic and special powers, even bringing the dead back to life.) Course VS takes place in Valendia (region where Archades Empire is located) and its briefly mentioned if memory serves me correct that cities utilize barriers to protect themselves from the normal amount of Dark that exists in the world.

I still wonder if the Occurians play a role though, seeing as they appear to have several satellites/cities in the sky that we saw when Lady Ashe met them in Giruvegan. I can't imagine that Vayne's Rebellion could beat them so soundly.