Are second tier social networks in trouble?

Techcrunch is reporting that leaders of the second tier social networks like Bebo and Piczo are leaving their companies. Can this be a sign of consolidation in the social networking space? Are the smaller players frightened by the might of Facebook, MySpace and Orkut? Its left to be seen what happens. I believe that there's a strong, vibrant market for the smaller social networks if they have clearly defined areas of focus, interoperability (yes, think OpenSocial) and something unique that draws users in. Otherwise, its only a matter of time before they lose their users to a Facebook or Orkut group.