I think that the web has already started to influence the majority of Americans on the big decisions in life.  Back in web 1.5 during the last election the blogs really started discussions, and made enough impact that their coverage on the elections, and other political issues, started getting reported in the mainstream media.  I believe that the blogs influence the outcome of the last election, and that web2.0 only makes that influence imbedded in more aspects of people's lives.