Warren Buffett has loomed large at Berkshire Hathaway's annual shareholder meetings, and this will be a key challenge as new CEO Greg Abel takes center stage.

For the first time, the 95-year-old Buffett won't be the central figure on stage, marking a new era for one of investing's most closely watched rituals.

Greg Abel made a point of stopping by every booth in the hall, greeting employees and shaking hands with shareholders.