The Smartphone is replacing the PC and repeating its pattern. Today the common laptop is a commodity, very little innovation and very slim margins. The smartphone is going the same way. (Just look how few new features the iPhone 5 has vs 4S or SGS2 vs SGS3). An out of contract high end phone costs about $500-600. For that money you get alot of laptop hw. From pure component cost the same price for a phone is not reasonable. Prices will go down in a race towards the bottom and that is a race Apple can not compete in. They will become a niche player with about the same market share as they have in PCs today (7% or so).
I agree to some extent that Apples market share will suffer as commoditization of the smartphone continues. But I also believe that the fact that Apple has created an "ecosystem" of products that are relatively well intergrated with each other will help their cause. And I expect Apple will continue to find ways to enhance this strategy. Many people/families will have mulitple computing devices in addition to a smartphone. For these customers this ecosystem approach will continue to influence buying decisionsfor years to come.