Kevyn Orr, Detroit’s emergency manager, cancelled a bus tour scheduled for today. He had hoped to give some of the city’s creditors a firsthand look at just how dire Detroit’s situation had become. Most declined. It’s one more sign of the many challenges he faces in trying to reach a deal among the city’s bondholders, government retirees and other creditors. Years of mismanagement, a shrinking tax base and groups of willing Wall Street investors have left the city on the brink of financial collapse. Bankruptcy remains an option. What’s ahead for Detroit’s residents, its unions and investors.