On the edges of Detroit, there are neat bungalows, tidy lawns and thriving shops. In the middle, miles of vacant lots and broken-down homes — so empty that pheasants are moving in. Basic services are too costly to keep up. Detroit is dying. So, Tuesday night, the new mayor, former NBA star Dave Bing, delivered some tough love for this struggling city. “I am unveiling a plan to demolish 3,000 dangerous residential structures this year,” he said.