The growth of

Pay would always be limited by the devices apple sells. This is a reason why Apple really can't do a full blown Social networking website, or

Pay like payment service that would look to establish itself as the leading payment service in the US or worldwide. Apple will most likely generate a lot of transactions through its iDevices, particularly as more retailers and banks are added and as more NFC enabled devices enter circulation. But beyond providing a service to its customers that makes their life easier, apple will most likely not focus on the "payments" aspect of the business and will continue to invest in things that it does brilliantly.