Actually the population is slowly being replaced. Detroit has become a tech boomtown with guys like Dan Gilbert (Quicken) who has imported some 12,000 people from all over the USA. There is a LOT of foreign investment going on as well.
https://www.youtube.com/watch?v=I-_uX2ZfqRI
I looked up the then current CEO of the Detroit tech effort Leslie Smith. She lives outside Detroit. I’ll bet that even if the tech companies locate there the employees so vital to the tax base will live elsewhere.
http://www.whitepages.com/directions/3c7fbc7a-faf4-4ea5-a30b-1de0780c4edd
When I worked for GD in Sterling Heights I was warned to never get off the interstate in Detroit. If I found myself in Detroit always leave maneuver room in front of your car so you can floor it in case of a car jacking.
There was an article on FR yesterday about the many, many dangerous places in Michigan. If tech companies are locating there follow the money. I smell crony capitalism.