I think you're spot on. Admittedly, I can't see Apple's downfall either, but that's largely because they're so dominant in the right-now. But history is littered with examples of huge companies that fail to adapt just like Kodak: Pan Am Airlines, Blockbuster Video to name a couple. These were giants in their field and have vanished. What often happens with companies like this is some other disruption occurs that undermines what made the incumbent special - in the case of Pan Am, it was Southwest, who innovated the customer experience and cost to fly rather than the focusing on flight tech itself; they did this by capitalizing on the deregulation of airlines; in the case of Blockbuster, well, we all know what happened there. I think the underlying root cause of the failure is when companies get large enough, they become too risk averse partly resulting from corporate inertia.
The one thing that Steve Jobs did well was recognize when adaptation was necessary. I'm not so confident that the bean-counter Tim Cook has that same ability and vision. Apple has to be careful. Personally, for all of Google's faults I've long preferred Android phones. They're not "open", but they're *more* open than Apple's walled garden.