Hypothetically?? This can already happen! Check out identi.ca. It uses Laconica http://laconi.ca/trac/ http://laconi.ca/trac/ which is "a Free and Open Source

Hypothetically?? This can already happen! Check out identi.ca. It uses Laconica http://laconi.ca/trac/ http://laconi.ca/trac/ which is "a Free and Open Source microblogging platform. It helps people in a community, company or group to exchange short (140 character) messages over the Web. Users can choose which people to "follow" and receive only their friends' or colleagues' status messages. It provides a similar service to sites like Twitter, Jaiku, and Plurk." I'm surprised no one has taken steps to avoid relying on Twitter.