Just finished a rough draft of the synopsis. I changed a few things, and I realized that "the last floating city" doesn't really apply anymore. I also changed a few things. Let me know if you're still interested, and if at least six of you are a yes, I'll go ahead and expand more on the setting. For a brief overview:

Domed Cities are inhabited by those wealthy enough to afford housing. Most live in underground cities that connect to the domes. The farther underground you go, the lower the standard of living is.

There are a few areas that are still habitable, but they use Etherius sparingly and live a more primitive lifestyle.

Most of the world has become a wasteland of abandoned cities and desert.

Damocles is a fairly small city mostly inhabited by the neo-humans (I actually need a name for this, too) and fal'Lucem employees.