Which reminds me of something I heard a few months ago
This year, at
Dragon*Con, Richard Hatch (of Battlestar Galactica fame) made a very interesting observation. It costs about $3M to produce an episode of Galactica (other Sci-Fi shows are similar. Shows without special effects tend to cost less.) A 4-episode DVD, therefore, costs about $12M to produce. If sold at $10 direct to customers (a bit more if sold retail, of course), it would require about 1.2-1.5 million purchases to break even. At its worst, Galactica's ratings have indicated 3-5 million viewers, and at its best, much more.
He mentioned this after observing a phenomenon WRT Galactica. The Nielsen ratings have declined over the first three seasons, but the fan response has been growing exponentially. This is because fans are buying the DVDs, they're making PVR recordings, and they're sharing their recordings with each other - none of which show up in the ratings. Even PVR recordings don't count unless the recording is watched within 24 hours of the broadcast, because the networks choose to look at overnight statistics and not long-term aggregates.
If a show like this is showing Nielsen ratings of 3-5M (which may not be enough to keep a show on the air), then it is likely that there are actually more like 7-10M actual viewers. More than enough to buy enough DVDs to keep a direct-sales show profitable. This is a golden opportunity for a production company to bypass the networks.
I'm not a businessman, but I think this model has merit, and I think we'll see a few production companies try it (at least as an experiment) in the near future. If the networks don't get on the ball by then, they'll be marginalized, just like the record labels are.