The Public and Social Networks

At DreamGrow Social Media, they recently posted a very interesting article about how there can only be one dominant social network. The public does not have time to invest in more than one network at one time, and to support this hypothesis, author Kallas pulls together a graph showing social networking market share over the past few years. View the chart here. As MySpace died out, Facebook has taken over it's share of having the most users. While many other networks remain used, Facebook is clearly the winner in the minds of consumers.

What do you think? Can consumers support more than one dominant form of social networking at once?