Eventually everyone will be on the web because the quarter that aren't using it are in two groups: older Americans and rural areas. Older Americans will pass on and wireless technologies will connect rural parts of the country.
You'd be surprised at how many people in their 30's missed "that whole Internet thing" and could care less.
I'm 28, my first exposure to the web was 1995/6 when I was in high school. However among my peers I was in the minority of people who actually used the web (even today).