There is loads of stuff from Planet Rollercoaster that fits very well with populated cities coming down the line:
NPC crowd movement, AI, context-awareness
NPC animations
Terrain types, different biomes
Terrain deformation caused by architecture
Modular buildings
Road grids
Dynamic texturing
Clouds (somebody said they are fully dynamic) and weather effects
All the pieces are coming together for the generation of populated planetside cities! Station interiors will benefit as well.
My dream would be that FD released tools for building and uploading cities and settlements. We'd have thousands of different layouts in no time, from backwaters to megacities. FD would of course have to check for cities and areas shaped like genitalia, but it would still be much faster than having the designers make them. It could be a beta perk. I'd love to visit a city I'd designed.
