Please make city maps and sell them. No licence needed, sure sellers.
This doesn't mean LFS would stop being a racing sim, it would just have more options which is always a good thing.
You've got great physics and decent graphics. The only thing holding lfs back is content and it's been like that for a long time.
Maybe there's a way to kick start a project for hiring 3D artists if man power is a problem.
If you don't wont anyone to have access to your source code, maybe you could import their work into lfs by your self.