The idea that revenue from Apple lines quickly fades after 2 years doesn't seem to square with history. Desktops growing for over a decade, finally fading due to laptop cannibalization. Laptops growing for over a decade, perhaps stable now and fading in the future due to tablet cannibalization. Music player grew for better part of a decade until heavily cannibalized by phone. Phone still growing 7 years after introduction. Tablets still growing 5 years in. But even if you throw their growth away and say they do 0% for next 4 years the market cap doesn't add up.
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:
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.
