Many years back Apple lost a huge amount of market share due to getting too big for its boots. Its doing the same again now. The whole iPhone craze is getting boring, each looks the same as the last, with a new iPad out every 4 or 5 months now people arent bothering to upgrade, iPods are vastly overpriced now compared to other music players, and iTunes has seen competition from other cheaper markets now like Amazon.
Their bubble is starting to burst, only today I was reading their share prices have taken a hefty tumble. There is only so long you can rely on the iPhone etc to keep your company in profit. Once people start getting bored of your products because with each incarnation they are too samey, then your in trouble. I think for the past few years Apple have relied on its fanbase who will lets face it, buy anything with an Apple logo on it, whereas many of this fanbase have now moved away from Apple and realised there actually better products out there, for less outlay.