Except that it wouldn't be an example of how a heavily regulated economy is the problem, because people who lived in the hypothetical future Detroit would likely be able to enjoy the unified benefits (social services, infrastructure, etc.) that come with better regulation. It's roughly equivalent to the "best of both worlds" benefit of tax havens in contrast to Western countries that tax fairly heavily. If you really wanted an example, draw a closed border around it and see what happens. I can't predict that, but it would be interesting to see.