Has Champagne lost its pop?

THE AVENUE DE CHAMPAGNE in Épernay, France, is the most famous address in the world of sparkling wine. Beginning at the Place de la République, the road stretches east through Champagne country—a straight line of villas and mansions housing some of the biggest names in fizzy wine: Perrier-Jouët, Pol Roger and Möet & Chandon. For three centuries, Champagne, an area of 30,000 hectares, was the only name that counted when it came to sparkling wine.