It’s a profoundly different feeling today than the last time Apple’s CEO announced his transition to chairman of the board, and his chosen successor was promoted to replace him as CEO. In August 2011, Steve Jobs was sick. For years he’d managed to stay a step, sometimes two, ahead of the pancreatic cancer he’d been battling since 2003, but no more. Jobs wrote , in his letter to the company’s board and the Apple community: “I have always said if there ever came a day when I could no longer meet my duties and expectations as Apple’s CEO, I would be the first to let you know. Unfortunately, that day has come.” Unfortunately, indeed. Cook inherited a company with extraordinary potential growth in front of it, but in deep existential grief. He led the company — and its community — through that grief and achieved that potential. The transition Apple and Tim Cook announced today is entirely different. No one’s hand was forced. There is nothing unpleasant. Apple’s business is firing on nearly all cylinders.…