Hmm after i think about it, yes all will die it. Just like facebook right now. It's become more easy to people to write something, their story, tutorial, sharing something, etc using facebook. For me, i feel it's more quickly to share something via facebook than blog.
and yes, facebook will die out also . It's normal, law of nature is excist on internet business, the most stronger and better will win. Do you know friendster 2-3 years ago is so booming (i don't know the case on your country), now FS is beat by FB