When Google startup, many people suggested that there are too many search engines out there and yet another search engine will not succeed. However, after Google, there is no major search engine emergence. For SNS, maybe there will be a next Facebook, but the chance is much rare than before. In Orkut/Friendster era, not so many people daily live on social network. For now, everyone online knows SNS and Facebook. That is the most obvious barrier for new comers, people's custom.
Everything is cyclical and doomed to fail until something better breaks that repeating pattern. It happened with Amazon before Web 2.0, when everybody thought it was doomed to fail. I'd bet it happens with Facebook.
It deserved repeating, because I don't think some people get it: Friendster had a few users. Myspace had a lot. Facebook has every single college student and now it has every single high school student, and almost every person checks it at least once per day, and in the last 6 months it's been picking up in every demographic. Facebook is a part of life for those people, in a way that Twitter or Tumblr or Flickr or even a huge site like Youtube is not. It's not going down without a fight.
YouTube probably doesn't deserve to be lumped with Twitter, Tumblr, or Flickr, but you're right -- Facebook has been a part of my every day fabric for a few years now, and it's only growing.
My parents, cousins, aunts, and uncles all use it, for goodness' sake.
Sites I'm in contact with every day: Facebook, Google (search, mail, reader), YouTube, Twitter, and HN.
As an aside, I honestly think Twitter will become very mainstream. I'm already seeing more pop-culture references every day, and have friends I never would have expected to see on it following me. It's certainly busted out of the Silicon Valley bubble, which honestly surprised me a lot. A year ago I thought of Twitter as the quintessential by-the-Valley-for-the-Valley startup.
> As an aside, I honestly think Twitter will become very mainstream.
I'm rooting for Twitter to succeed independently (e.g. not acquired by Google or Facebook).
I think I started suspecting Twitter was reaching out to the mainstream (or at least the younger generation) when I would click on random public timeline and/or summize search result rows and find people who had 40-50 followers, talking about what was going on in their life (e.g. normal, average people not social media cultists)
The power of Twitter is that is like a cocktail party laced with real-time search capabilities.
