The Economist recently had an article on social media's impact on blogs, especially how sites like Facebook have meant the death of a large number of blogs. I have been thinking recently about this myself. I haven't posted on my own blog for over 6 months, partly because Facebook's status updates has fulfilled part of my communication needs. Partly because I've been going through a phase of focusing on work and reading, and haven't been interacting much with my social network.
I do think that blogs have a part in our future - I just think that the people who used blogs as a telephone will move to Facebook, those that used blogs as a form of SMS will move to Twitter, and those that feel the need to expound on a particular topic, and want their missives to have a greater scope and longevity will continue to use blogs.