Detroit sounds like an opportunity for a foreign power to move in, buy that real estate and colonize it, like in Africa
China maybe?
Buy up blocks at time, secure them, then renovate them. Do it again as each neighborhood is reclaimed. Use a type of indentured servitude employee, a small salary, housing and food. Have them work at security and remodeling. Teach them skills in the trades. Open general stores at first. Build small production factories making anything. Start a trucking company.
The perfect people to do this are the young unemployed, especially from rural areas as they will already know how to use guns, some tools and machinery. Give them the adventure of re-birthing a city with the promise of a house after so much work. All the while indoctrinating them with American spirit and conservative values.