In the 22 years I've been at Arkansas Business, Walmart has turned over its modest executive suite three times: David Glass to H. Lee Scott, Scott to Mike Duke, and Duke to Doug McMillon. Each time, the CEO title went not to an outside hire, but to another executive inside the company. Both Duke and McMillon led Walmart's international division before rising to the top. Its current CEO is U.K. native Judith McKenna — someone who would be a fascinating choice to succeed McMillon.