Technological cannibalization seems to be the norm and no one is more aware of this impact than Apple. When they introduced the iPhone, many worried that iPod sales would be hurt. And they were right. But the innovation of the iPhone, while cannibalizing iPod sales, also enabled Apple to succeed. The same cycle is now repeating with the iPad.
While iPods continue to sell, they represent a smaller business then before. With the introduction of the iPhone 6 and 6 Plus, Apple recognizes that it will cannibalize sales of its iPad. In fact, it could lead to the drop of the iPad Mini model. At the same time, the iPad may fine more uses in business sectors then in the consumer market. And as iPhone sales makes iPads less desirable, they may also help sell more laptops.
With the MacBook Air and MacBook Pro getting lighter and more powerful, Apple users may find these products, linked with their larger iPhones as the perfect combination. MacBook sales in general have been rising as PC sales are declining. This trend seems likely to continue.
For Apple, they seem to have no problem letting cannibalization occur. It is in their best overall interest to not try to save declining products but to focus on the synergy of their total product line. With the introduction of the iWatch in 2015, that synergy is likely to continue.