Why do sales always need to grow, why sustaining is not enough?
Also wouldn't it be a good idea to change the focus product periodically? I.e. we've sold so much iPhones that everybody who ever wanted one has one already, let's focus on making MacBooks great again so more people would consider getting one or upgrading their old one, then once some time has passed and everybody has a new Mac let's start selling new iPhones we were developing during this time that is so much better thst everybody is willing to upgrade again... IMHO inflating sales growth by releasing a new not-much-better model of the same product every year or two is hardly a healthy sustainable practice.