The Internet will be shaped by how humans want to do things. Among the disadvantages I see is a possible widening of the gap between the haves and the have-nots. There's also the issue of privacy. And, the fact that you can belong to all these communities on-line means that, in a sense, you belong to your physical community a bit less. The U.S. has had that problem more than most countries, even before the Internet came along.
People are more mobile and move to different areas.
We already have some of the ills that come when people don't feel engaged with their neighbors. By the way, some people say all the change because of the Internet is going to happen in two years. It's not going to happen in two years. I think we're really looking at a 10-year time frame. In 10 years, the behavior changes will run so deep that they'll be taken for granted.