Anyone interested in the future of the Internet should be watching the current situation in the radio industry very carefully. The decentralized nature of the Internet makes it hard to imagine a future where a few dominant companies control most of the content. If alternative business models to advertising aren't found for the Internet, though, I'm afraid centralization and concentration could happen—just as it has in every other advertising-supported medium.

Somewhat related: Salon's subscription plus advertising model doesn't seem to be working.