Here is one of those "the blogosphere is ten years old" articles: The Blogosphere at Ten – Britannica Blog. It’s a tad cynical, and misses out completely on some of the benefits of blogging: the psychological upside in terms of self-expression, the social aspects of "meeting" like-minded people that one otherwise could not, and so on; but basically a realistic analysis, I think. It does end on an upbeat note:
But others may actually make a contribution to what this crew of encyclopedists calls the great conversation. We live and breathe to bring the views and learning of experts to the world, but that does not mean that the discourse cannot include voices that have not been heard before. Far from it. When you find them, I pray you, please throw some hyperlinks this way—even at the risk of subverting hierarchy.
(Another Britannica blogger, Andrew Keen, has a far more negative view, here.)