There's one issue that can severely damage two of them: Facebook and Google's business value come completely from taking away privacy. Apple, Microsoft, and A

There's one issue that can severely damage two of them: Facebook and Google's business value come completely from taking away privacy. Apple, Microsoft, and Amazon also do so of course, but they can offer strong business models that doesn't should the need arise. They won't be as profitable, but they won't die either. At the moment Americans don't care about this issue, because they balance the lack of privacy against their fear of terrorism. But if they start to care things could turn around in a hurry for those two and we would see an interesting scramble.