Maybe it wasn't about the market sector. Maybe it was always a political/ideological issue.

When I was a youthful econ. major (late 1970s, early 1980s), Detroit was an example of urban decline driven by economic conditions.  There were still, just, fitful major programs of public policy and private-public investment attempting to resurrect the declining city.  Or to at least halt the decline.  Nothing worked.

The general story line was that Detroit's problems were instigated by, and then exacerbated by the continuing decline of the American automotive industry.  Sure, bad public policy, political corruption, and poor state capacity all contributed to the nightmare, but the central issue was economic decline from a particular industry.

Since then, New York City's serial cycle of decline and resurrection, compounded by the economic suicide, led by politicians, of San Francisco, Los Angeles, Chicago, and now, again, New York, have cast that earlier morality tale into question.  Almost to the point of refutation.

Urban decline is a selected choice, not some random economic/industrial cycle of decline.  Electorates choose ideological and incompetent leaders who then blithely lead the city into an accelerating cycle of ruin.  

IowaHawk captures it:

Click to enlarge.