You could probably not get a much better example of the classic product life cycle graph than this one which charts the sales of ipods from their introduction in 2001 to the end of 2010. And the graph also reveals two very interesting things which should be mentioned when teaching the product life cycle.
Firstly, the “extension strategies” employed by Apple contribute to the classic shape, rather than the usual textbook examples of changing it. These include the introduction of the ipod nano as well as the ipod touch.
Secondly, the decline phase is usually explained in conjunction with the introduction of competition from other firms but in this case it is attributed to the success of Apple’s best selling product - the iphone.