Post hoc, ergo proper hoc? I don't necessarily disagree with you, but don't you think that there might be more contributing factors? In particular, the decline of the American auto industry comes to mind in regards to Detroit.
There's just very little incentive to live in the city itself anymore between the lack of small businesses, crime, etc. I heard a story of a guy who purchased an entire block of houses, demolished them, built new condos and was waiting on city inspection so people could start moving in. Inspection took a while and in the meantime the newly-built condos were broken into and stripped of any valuable piping/wiring. Does that really a place you want to live in? The only reasons I go into the city are for sporting events, the occasional concert, or urbex.
The segregation of Detroit and its metropolitan area are SHOCKING. Look at this map: http://bit.ly/ptgVNe
The blue is African-Americans. The red is Caucasians. The all-too-clear division begins at 8 mile.
Some sort of link has to be established in order to unify the suburbs and the city. Hopefully the M1 rail project can be that link -- unfortunately, like I said in another comment, the rail has to stretch further into the suburbs for it to have any chance of success, IMO.
The fact that Twelve Oaks Mall is nice and has an Apple Store doesn't mean that that the Detroit Suburbs are proof of a functioning greater Detroit metro economy.
Higher up in this thread, I referenced the book The Slaughter of Cities, by E. Michael Jones. That is the book around which my views have gelled.