Ah, the amusement that comes from Op-Ed pieces...
$1 Trillion? Really? I'm not sure Microsoft's peak value combined with Apple's could quite reach that figure. And this is one of the more poorly informed Op-Ed pieces I've seen in a while. Makes me feel like an expert for some of the commentary I've done on podcasts.
Among other things, there is a developing watershed moment with social networking sites. In April alone, Facebook lost over 6 million users. They didn't even have Google+ to blame for it. They just up and left.
And to claim Google as being a peer to Facebook is preposterous and entirely out of bounds. Facebook and Google+ do clearly compete. But, that's pretty much where the comparison stops. Past that, Facebook requires you have an external email address to create an account; Google GIVES you one. Facebook displays your geographical location with "check in" by way of Bing; Google made their own map and location system. The comparison braking could go on and on.
While, Facebook is worth a large amount of money, it's very conditional. It is dependent upon subscriber uptake and retention. And within that, it's dependent upon those subscribers clicking ads. And a lot of us are using software to block ads and behavioural marketing tracking apps and the like. To that end, Facebook will continue to incrementally lose it's hypothetical value. And as that carries on, it will continue to lose real-world valuation.
In the end, it is extraordinarily unlikely that Facebook has or ever will reach as high a value as the author of this article seems to think.