"Tim Cook's the guy who makes the trains run on time. He's not the creative genius," Kay said. "Even though in some sense he is an excellent manager and is the backstop for Steve ... that's not going to do anything except make the trains run on time. That's not going to decide what the train should look like in five years."

Still, Jobs' absence is unlikely to affect short-term product plans, which will already have been decided, Kay noted.

(Agam Shah and James Niccolai in San Francisco contributed to this report.)