Soon Apple's hardware ecosystem will be complete
Coming down the pike is a low-cost iPhone, a Big iPhone, an Apple Television, and even an Apple Watch. Perhaps further down the line you have a something like Google Glass (when it's more practical) or maybe a bigger iPad (say, 13 or 15-inch). But that's pretty much it. Apple isn't about to make a refrigerator.
At that point, they'll just be refining and improving their software, services, ecosystem, and existing hardware. There will be new products, of course, such as new services (mobile payments? iTunes subscriptions?) and new interfaces (gestures?) but the hardware ecosystem will be just about complete.
At least, I can't think of anything that makes sense for Apple. Can you? It would have to be a product that has mass appeal and is somewhere in their wheelhouse (i.e. consumer electronics).
We occasionally hear about fitness as a possibility but it seems as if a watch-like device covers that. I mean, they're not releasing an exercise bike or a scale.
Any other ideas?