The Slow Erosion of Google Search (A "guessay" by Joshua Porter)
So while Google continues to increase its search market share, and folks look at that and say “Google is only getting better”, what they don’t necessarily see is how much the social sites are sucking up more attention. And eventually that attention will be so strong that Google will begin to suffer.
Advertisers will probably still use Google for a long time. But where will they go first? They’ll go first to where there is the most attention, and I think social networks will eventually claim that lead.
Joshua’s guessays are hardly what I’d consider speculative.