Amazingly, Apple surpassed that total in 2015 by selling a record 74.8 million iPhones. But unless Apple has a spectacular three month period from January through March, the device will indeed suffer its first decline in sales year-over-year. Pacific Crest Securities analyst Andy Hargreaves recently cut his estimate on Apple's earnings for the quarter as he expects iPhone sales from January through March to register at the low-end of Apple's range.
This year-over-year decline in iPhone sales should be short-lived. Next quarter, we could see some contribution from the 4-inch Apple iPhone SE. The following quarter after that, the new design of the Apple iPhone 7 and Apple iPhone 7 Plus should lead to stronger sales year-over-year. There is a good chance that the current quarter is an outlier when it comes to year-over-year iPhone sales.
Apple does have a large number of potential buyers that can make a difference in any given quarter. 60% of Apple iPhone owners who were sporting an iPhone at the time the Apple iPhone 6 was released, have not yet updated to a device with a larger screen. And if they don't want an iPhone with a larger screen, perhaps they want a more powerful 4-inch model like the upcoming iPhone SE. Either way, it does add up to a large number of potential iPhone buyers on the sidelines, waiting to make a purchase.