what would case facebook to die? I don't see it happening anytime in the next 5 years. Maybe in another 10 years when there is a huge para dime shift, but overall at the current moment, I don't think this is happening.
I use facebook alot but I never ever publicly post any personal info on it. Hell I don't even use my real name on it. And signed up to it with a fake email address. Still my real world friends add me on it because they recognize me by my first name and my facebook profile picture of my handsome face :-)
Facebook has become more of a phone directory now than a myspace-esque social media site. It won't die unless a better directory comes along. Even if there is a new "MySpace" Facebook will still be around simply because of the way it is organized and set up. People have actual names, actual photos, and various details about their lives (relationship status, work, where they are living). Other sites are basically planets revolving around the Facebook sun. They can come and go, but Facebook will continue on for awhile - at least until Web 3.0 (whatever that will be) is underway.
I got tired of social media years ago. I was addicted to MySpace for awhile, but sites/apps that promote sharing your entire life with the entire world just seem creepy and unnecessary to me at this point. I have a Facebook, but only check it time to time, and never post anything. My gf used to facebook a lot, but I never hear her talk about it anymore.
On a side note, I still remember the first social site I used in College, probably around 2001-2002. It was called hotornot.com, and it was essentially just people posting a profile + pics and getting votes for being hot or not. Maybe people were using it to hook up also, but I went to a party school, so the idea of trying to hook up with chicks online never really crossed my mind to be honest.