User blog comment:The king of war/The Beta/@comment-109.158.23.228-20120613163042/@comment-1992639-20120613175042

Or the Falmer are merely a side-product. While the Dragons burn down entire holds, the Thieves Guild, cutpurses and even merchants propser from the chaos. If the sun is out, the Falmer won't have to stay inside the caves. The same as how Ice Wraiths and Frost Trolls could live everywhere if without the sun Skyrim cools down, causing it to be frozen everywhere.

I think the Falmer will be one of those side-questlines the developers mentioned in the interviews, with a few quests making up the story.