Well the Alik'r desert takes up a good portion of their homeland. There will probably be some cities in the desert too.
Stros M'Kai is an island and a major seaport. Hopefully the Thalmor haven't taken it over.
I'm curious about the status of Skyrim. I wonder if Bethesda will mention the winner of the civil war in Skyrim. When I played Skyrim I chose the Empire because Ulfric was just power hungry and realistically an independent Skyrim would get destroyed by the Aldmeri Dominion. Then again the Emperor did get assassinated by the Dark Brotherhood so the Empire is probably in chaos due to deciding who will be the next Emperor.
Also Ulfric is essentially an asset of the Thalmor :
Skyrim:Thalmor Dossier: Ulfric Stormcloak - The Unofficial Elder Scrolls Pages (UESP)
The Dragonborn is probably going to be still adventuring somewhere and I doubt they will make an appearance in Elder Scrolls VI.
The Nerevarine (Morrowind) is old and probably in Morrowind or Akavir.
The Hero of Kvatch (Oblivion) is the daedra prince Sheogorath: