Both were actually just formulated while I was attempting to put the very basic and general premise into words.
But I think this is as much as I got for now.
I think emphasising the constant struggle to keep the centers of civilization from collapsing instead of having things revolve around control of rare resources gets a much better impression of what the ordinary PCs are dealing with.
I think where there still is a clear white spot is in regard to the future. A permanent struggle for the survival of cultures is a starting point, but I think some kind of look forward should also be there. Not becomming masters over all of nature, that certainly doesn't fit the setting. And I also dislike growth and expansion for its own sake.