That's predictable for a Republican speechwriter. It's incomplete: it was Cicero, not Dearborn, that broke Martin Luther King's heart. A bilateral monopoly-monopsony that divides unsustainable monopoly rents will come undone, racially motivated union-busting tactics or not.
Two other factors have to be considered.
The first is the especially and maybe uniquely poisonous quality of Detroit’s race relations. Like Chicago, Detroit attracted hundreds of thousands of black migrants between 1915 and 1960, mostly very unskilled, hoping to gain well-paying employment in factories and warehouses.
Their arrival jeopardized the ambitions of the white working class to raise its wages through unionization. Henry Ford eagerly hired black workers in order to defeat the unions, and in the violent labor clashes of the 1930s, whites and blacks often confronted each other as strikers and strikebreakers.
After the war, the United Autoworkers union tried to integrate blacks into the industrial workforce. But by then automation had begun, and industry’s demand for unskilled labor would first cease to grow, then diminish, then disappear. For many migrants, the promised land soon proved a mirage. Or maybe worse than a mirage. If the promised land did not yield the hoped-for industrial jobs, it offered something else: generous new welfare programs, the ashy false fruit of urban liberalism. The children of the parents who accepted the fruit grew into the criminals who drove first the middle class and then the working class out of the downtown and then altogether out of the city.
That crack about Wayne State (for whatever it's worth, the economics department there made me look so good that Northern Illinois made me an offer I couldn't turn down and Wayne's administration wouldn't match) elicited one angry comment at Mr Frum's site. Southeast Michigan is home to Motown, Madonna, and techno. Judge those cultural contributions as you wish. The social scene, as covered by the newspapers when I was there, tended to be dominated by plastic people who enjoyed such things as powerboat races on the Detroit River and the Grand Prix races, the only time the city streets were clear of Michigan drivers. (They're worse than Illinoisans on average.)
The second factor in Detroit’s decline is the city’s defiant rejection of education and the arts. Pittsburgh has Carnegie-Mellon. Cleveland has Case Western Reserve University. Chicago has the University of Chicago, Northwestern, and a campus of the University of Illinois. Detroit has… Wayne State.
A city that celebrated industrial culture spurned high culture. The Detroit Institute of Arts is very nice. But it does not begin to compare to Cleveland’s museum, let alone the Art Institute of Chicago. Detroit has a symphony orchestra, but its history has been troubled and unstoried in comparison to Philadelphia’s or Cleveland’s. On the plaza in front of the Detroit municipal building is a huge bronze replica of Joe Louis’ fist and arm, as if to say: “Here is a city ruled by brawn.” Brawn counts for very little in the modern world.
I found the article by way of a Stephen Henderson column in the Detroit Free Press (motto: if the Evil Emperor dies, you'll read about free-agent issues facing the Detroit Lions first) in which the comment section is spirited, if frequently showing evidence that the area was settled by Appalachian sub-literates.