I think people have been reading too much cyperpunk if they think that being a large technology corporation confers long term survivability.
Remember ATI? Not as bit, sure. But when your in a market as fluid as one subject to moore's law. Fortunes both rise and fall very fast.
As I've said, considering Apple become huge largely due to a particular aesthetic style cooked up by a man who is now dead. What keeps them big exactly? Gradually becoming more and more mundane and everywhere?
A lot of their patent action as of late could be explained as their leadership being conscious of this.
Not to say Google is somehow in a position protected by the angels. They however just won a couple of rounds with Microsoft (anyone using bing yet?) and android is hip amongst people who spend far too much of their disposable income on technology.