While I was looking for something completely different, I ran across The Internet Slum: Is Abandoning the Internet "The Next Big Thing" by John Walker. (For those of you who aren't geeks, John Walker is the founder of Autodesk--you know, the publishers of AutoCAD?) He makes an interesting point that there are people who are abandoning the Internet because it is turning into the electronic equivalent of a declining neighborhood.
The reason I find this interesting is that I've had similar discussions with some of my coworkers. Between attacks, spam, spyware, popups, popunders, trojans and viruses, my computer spends as much time defending itself as it does handling my requests. Add in the fact that I have small children whom I don't want exposed to the seamier side of life just yet, and the idea of ditching the Internet altogether has a certain appeal.
Developments in this area will be interesting. As Walker says, you won't really notice that people are dropping out, but you will see the it in the second derivative.