The city of Detroit has faced serious economic challenges in the past decade, with a shrinking population and tax base while trying to maintain essential services. 

With its bankruptcy filing, the city of Detroit has entered uncharted territory. It's a dark place that no major U.S. city has ever gone—but that could change.

Despite the uncertainties surrounding what's expected to be a hard-fought legal battle, the outcome promises to inflict more pain on Detroit's already-beleaguered residents, businesses, creditors, investors and city workers, whose pension plans may now be invalidated.