Under Cook’s leadership—both as CEO and before that as COO—Apple brought its most important technologies in-house. It designs its own chips, manages its own supply chain, and oversees a services ecosystem that generated nearly $100 billion in revenue last year alone.

In a new Fortune article, my colleague Geoff Colvin highlights the dilemma facing Apple CEO Tim Cook. Chief executive since 2011, Cook succeeded Steve Jobs after serving as Apple’s chief operating officer. As COO, he was responsible for the company’s worldwide sales and operations.

Research firm LightShed partners says Apple should consider replacing Tim Cook as CEO, but the change is unlikely to occur any time soon. In a