Given all the security issues that Facebook has had to deal with, I'm not so sure about this. My account has been hacked a couple of times despite switching to much more sophisticated passwords. But there is no denying the impact Facebook has had on society so I guess Mark Zuckerberg being named Time "Person of the Year" was something of an inevitability:

Facebook has merged with the social fabric of American life, and not just American but human life: nearly half of all Americans have a Facebook account, but 70% of Facebook users live outside the U.S. It's a permanent fact of our global social reality. We have entered the Facebook age, and Mark Zuckerberg is the man who brought us here.

The question about all such revolutions is will it last? The technologically hip young are driving innovation on the internet, but have notoriously short attention spans. Will Facebook usage fade when The Next Big Thing comes along in social media?

My guess is that in 5 years, Facebook will still be with us but will have morphed into something entirely different than it is today. That is the reality of life on the internet and Facebook will not be immune to the constantly changing methods of online communication.