Open-source vendors: Monopolies waiting to happen?

JBoss developer Roy Russo wonders if all open-source companies are de facto monopolistic. Like many others that I respect (Dave Rosenberg, Lonn Johnston, President Bush, Oscar the Grouch), Russo says any market ultimately has room for only one purveyor of free software. He writes:

"(Open-source software) companies focusing on proprietary competition win out in the end, but if history is a guide, they also manage to squash their own OSS competitors by doing so."

Open-source vendors: Monopolies waiting to happen?