Social networking sites of today have a design flaw, besides having the known privacy issues.
Though these sites may make a person feel like a star, they make all his friends listening to him as his “followers” or his audience.
The one-to-one relationship which friends crave in a friendship is changed to one-to-many relationship where previously close friends find themselves as just one-in-many.
This may not be acceptable to many people. I suspect that it would lead to other competing sites to spring up which can provide both better privacy as well as the feeling of a close relationship with your friends.