Volkswagen CEO Matthias Mueller speaks at the North American International Auto Show in Detroit on January 10, 2016. Mark Blinch / Reuters By now, Volkswagen’s explanations, apologies, lawsuits, and goodwill programs have all had their turn in the headlines. But a central question still remains unanswered months into the fallout from the company’s emissions-cheating scandal: What will happen to the 11 million offending “clean diesel” vehicles worldwide?