REIMS, France — Back in 1996, Jean-Baptiste Lécaillon, a young assistant at Louis Roederer Champagne , took on the daunting task of forecasting the next 30 years for the venerable house.

How would the world change for Champagne? And what should Roederer do to adapt to those changes?

The project required a far-reaching understanding of science, politics and wine, and it meant looking both to the future and the past. Although few foresaw it at the time, Champagne was on the brink of a revolution that would transform how the rest of the world looked at the region and its wines, and how Champagne viewed itself.

Mr. Lécaillon was hardly an obvious candidate to take on this study. Just 30 years old at the time, he had joined Roederer in 1989 with degrees in agronomy and oenology. He had seen wine operations in other parts of the world, working on Roederer projects in California and Tasmania.

But he had been marked as a future chef de cave, or head of the winemaking team, and had worked closely with Jean-Claude Rouzaud, then the head of Roederer, whose family has owned the house since Louis Roederer gave it his name in 1833.