The problem apple will be facing soon is that they're nearing the end of possible permutations of the screen + touch input devices. They took the mp3 player, made it more accessible, then they made it bigger, then they made it a phone, then they made it a tablet. The problem is not so much that the devices won't be there as they will be commoditized. When that happens, only the cult of Mac will be paying through the nose for the hardware.