I get what you are saying. My point is that even in the same product line, e.g. phones/tablets, there is no guarantee that Apple will be able to sell the same n

I get what you are saying. My point is that even in the same product line, e.g. phones/tablets, there is no guarantee that Apple will be able to sell the same number of iphones/ipads in a few years. Case in point: http://en.wikipedia.org/wiki/BlackBerry_Ltd#Financials http://en.wikipedia.org/wiki/BlackBerry_Ltd#Financials BB was growing like crazy for the whole decade till 2011, consistently ~40% year over year both in revenue/profit AND users. Just a dink in 2012, and kaboom, you know the rest of the story. And note that enterprise email was supposed to be the unbreachable moat for a business.