Imo, one of the big problems is the whole city is a brownfield, too much liability to assume to rehab or re use any part of Detroit.
Probably every building that is salvageable or suitable for reuse won't meet code. In the grand scheme of things, we have outlawed Detroit.
You want people in Detroit, the starting point is a school system. There's money to invest or rebuild but you won't have anytakers because where are you going to send your kids to school?
Ha! Detroit was once known as the "Paris of the Midwest".