Though massive, the iPhone business has plenty of room to grow because only a small fraction of Apple's installed base upgraded to the latest iPhone 6 and iPhone 6 models. Fewer than fifteen percent of recent Apple buyers had an iPhone, with the remaining 85 percent of sales coming from switchers who used to own a non-Apple handset, in most cases Android.
That's the gist of an interview Apple CEO Tim Cook gave to the Wall Street Journal's last evening. In other words, the vast majority of new iPhones were purchased by former Android users.