Tim Cook is Apple's chief operating officer and ran the company for a short stint while Jobs was undergoing cancer treatments several years ago. Cook could replace Jobs because, in essence, he already runs the company.

Steve Jobs isn't bogged down by making decisions about payroll increases, that falls to Cook. Furthermore, Cook has been known to be just as demanding as Jobs when it comes to driving the business, dealing with problems and plotting a course into the future. It was Cook, after all, who got Apple out of the manufacturing game, a move that's saved the company mountains of money.