Salesforce CEO Marc BenioffPhoto by Kimberly White/Getty Images for Fortune Benioff just shook up Salesforce's leadership, bringing several former execs back to the company. The changes shifted more responsibility to President and COO Brian Millham. Benioff and Millham talked to Insider Editor-in-Chief Nich Carlson. Salesforce CEO Marc Benioff just announced a shake-up that re-staffs his brain trust with an armful of boomerang executives.The changes shift more responsibility to president and COO Brian Millham, and go some way toward addressing investor concerns about succession -- should Benioff decide to pass the CEO reins in the future.