Do we only need virtual friends?

There is a world wide craze about social networking sites. There are as many variations as there are people with any kind of IT skills.

The question i want to ask is this:

1. Do we only need virtual friends? Are we going to give up on our real friends?

2. Ad revenue from social networks so far is not enough to provide organic growth. What is the future of these social networks as business if their ad revenues are not high enough to cover costs?