Kotter spoke with CNBC about Apple's leadership transition under John Ternus, the new CEO, and the challenges faced.

Kotter is the authority in adaptability and transformation. We help individuals and organizations better adapt and lead change via world-class consulting services and leadership development training, including the Kotter Change Certification Program.  With offices in Seattle and Boston and team members located across the world, our consulting practice help organizations accelerate the implementation of their most critical business strategies. Our tailored leadership development programs help build urgency for change, prompting mindset shifts and enabling people to become better leaders. We relentlessly ask the question: If the world saw more leadership from more people, what could change? We believe so much more is possible. Our new book, Change: How Organizations Achieve Hard-To-Imagine Results in Uncertain and Volatile Times, is available now for pre-order. Get your copy today. https://www.kotterinc.com/book/change/