I don't have a lot to say to this except that I am not surprised at all. Detroit has been floundering for ages now, and it was literally only a matter of time. I live less than an hour away from the D and despite it being the biggest city in Michigan it has no tourist appeal at all. I only go there maybe once a year, at best. It's pretty sad that the suburbs have a lot more going for them on a recreational level than the city.
I worked at a mall that was an hour drive from the Canadian border, yet most of our out-of-town customers were Canadians. I talked to a few at work and they drove right through Detroit to get to the mall, as it was more of a point of interest than the entire city of Detroit, apparently.