I think if Apple's sales were going to flatline because of saturating the market for high-price computers, they'd have already done so. (Which isn't to say they might not flatline or even decline for some other reason, sustaining this kind of growth probably won't last forever).
Apple currently has ~10% PC market share in the world‡ (higher in North America, but let's be conservative).
They still have a long way to go before running out of people to buy their computers.
‡ http://osxdaily.com/2011/03/18/mac-market-share-around-the-w...
Right now Apple is doing great. I would still question the sustainability of this business as an investor. What's next after ipad?
Long term, 5 years say, ipad/iphone margins will evaporate and Apple will need a series of "big things" to fill in the gaps to even have a flat growth curve to justify their market cap - that's my prediction.
I think your comment is a bit of hyperbole, the success of a company like Apple is not unprecedented in history. Apple could continue doing "big things" over the next decade, I just seriously doubt their ability to continue their growth and justify their market cap over the next 5-10 years. That's all. Possible, yes, in my opinion extremely, extremely unlikely.
And also like clockwork, I had a comment explaining why I thought they would fail, and have downvotes.
Apple is not afraid to kill its cash cow if they think they have a better product in line—see how they dealt with iPod line before the iPhone—they were replacing the most popular model with something new.
I have no doubt Jobs has a vision many years into the future. It was amazing to watch his 1997 WWDC keynote and realize that now we see the fruits of his thoughts then.
Who knows, but I’ve learned not to bet against Apple too often. Who would have foreseen the popularity and success of the iPad just a couple of years ago? The iPhone is barely four years old and has dramatically changed the industry as well.
They grew the market for smartphones and tablets, and they'll probably continue to do so. It's still a long way to smartphone and tablet saturation.