What's up?
Like any other city and economy, Detroit will need to reinvent itself. It will be painful, abrupt for some people, and so on, but economically, it has to be done. The industrialised world is turning into a knowledge economy, not a car-manurfacturing production facility.
Just for reference, Montreal went through a mini-evolution phase a few years back. IIRC, St-Laurent was dead, no real buildings going up, etc... now for the last few years, things have been going good again
Ciao!