I'm a Detroit resident...lived there my whole life. Here are the major factors to the Detroit Paradox in particular.
1. The Infrastructure: The problem now is that through terrible legislation, corrupt government and shrinking tax base the infrastructure of Detroit is eroding. To make it worse Michigan has really oppressive laws when it comes to things like traffic tickets and misdemeanors and thus many of the people who are able bodied and CAN work, can't, due to suspended licence (which leads to jail time after 2nd offense on top of over $1,000 in fines) or records that would inhibit employment her but not many places else. This is POISON to a city that has never had fully functioning mass transit due to lobbying from the big 3.
2. BLACK FLIGHT IS REAL: Many black folks who have been life long citizens such as my self are quick to leave the city and move to the suburbs of Southfield, Warren, Ferndale ect. Places that geographically TOUCH Detroit but remove vital tax dollars from the city. There's a plague of people complaining about the city but refusing to contribute to the base, thus sapping the city of resources that would perhaps save the city. This goes back to the infrastructure problem in the fact that many educated, successful blacks don't feel safe in the city.
3. Regionalism: All major metro areas in America are functioning regions as well, Twin Cities, Chicago and its suburbs, Dallas-Ft. Worth, SO-CAL, NO-CAL, DMV area ect. All of these places have mass transit and systems in place that made the work forces of both the city and the suburbs able to flow freely and efficiently. Legislation was also in place to make sure than the burbs could still funnel money back into the city through white-collar workers and the city could maintain its blue-collar and service tax base as well as its 1% which usually choose to live in the downtown areas of said cities. Detroit NEVER had that, in fact Oakland County (northern neighbor to Detroit's Wayne County, and one of the richest counties per square mile in the COUNTRY), often REFUSED to assist Detroit when it came to regional legislation.
However, as racially charged as this sounds white folks are "coming to take the city back" many areas are already in a state of gentrification and lots of recently graduated Caucasians are revitalizing areas that were hard hit by the recession. Midtown Detroit in particular has seen a major boom in not only its population but also in small businesses, which are owned by mostly whites. What does this mean for poor, lowly educated blacks in the city? Well...you are going to have a ghost population that live in sectors of the city that can't afford what even goes on in the place in which they live. In other words....this time 10 years from now Detroit may not be the bastion of Black Industry and Government it once was....and that might be what it takes to revive it.