I do not think that Detroit will be able to recover.
The days of heavy American industry are probably over, because there's hardly anything that America can do that can't be done somewhere else more cheaply.
America could let the dollar fall in value so that its products are cheaper for the rest of the world, but China owns trillions of dollars, locked away in the bank.
If the dollar falls, the Chinese government loses money and it's unlikely the Chinese government would allow that to happen without serious repercussions.
I come from a part of Britain which has been pretty much devastated by the collapse in heavy industry here. What matters most is that the government manages the decline and finds other ways for places like Detroit to make money.