Detroit is bankrupt and losing money because it has lost much of it's automotive and manufacturing industry that made it grow in the past. It was also harmed by area banks. I believe that Detroit must file for bankruptcy and hopefully the city will someday start to be able to recover and prosper again.
The people of Detroit who have settled there and built their lives there should not have to live in a bankrupt city. For many of them there is probably not a way to leave and move to a more prosperous area. This is a problem brought on by people who should have been capable to run the city and make it prosperous, or at least sustainable. Honestly, I don't know what the impact would be on the population, if their conditions of life would improve, but it just sounds like somebody or many people failed and now want to walk away.