Interesting. I disagree with each one of those sentences.

I think the choice would be pretty close, not something where you could pick without a doubt.

Facebook is definitely not just the social network du jour, just as Google wasn't the search engine du jour when they appeared. (Though people could have claimed with equal plausibility that they were.)

Thus while there may be a "next Facebook" in the sense of the next hot startup, it won't be doing the same thing.

And I feel like I'm a friend of both companies, both in the sense of knowing a lot of people at both, and thinking pretty highly of both. And choosing between the two of them would be hard.