Here's a real "blue sky" urban design. A small city mounted on huge caterpillar tracks allowing it to move around:
In a world where people live more mobile lifestyles than they have for centuries, cities are facing a problem they rarely planned for: their citizens move away. When jobs and resources start to decline, modern cities, such as Detroit, suffer difficult and often wasteful processes of urban contraction. In contrast to this, Manuel Dominguez’s “Very Large Structure,” the result of his thesis project at ETSA Madrid, proposes a nomadic city that can move on caterpillar tracks to locations where work and resources are abundant.
At ArchDaily, with lots of pictures. H't Tyler Cowen.