Trend: Traditional television content is becoming available from many sources.
CBS ... is moving from subscription service to ad-supported video streaming for next year's NCAA basketball playoffs, which will greatly expand the viewing audience and most likely the revenue for the network and the NCAA.
The NCAA will continue to make money from its DirecTV all access deal, but now a much larger audience will get to see more of the games. Why wouldn't advertisers want to be seen by an audience of mostly broadband (and therefore more affluent) customers, and where they can structure their fees based on actual viewers, not Nielsen estimates?
CBS probably looked at the success that America Online had with Live8 this year before making its decision. Like March Madness, Live8 had multiple performances going on at the same time, so streaming the alternatives enabled the company to maximize the number of viewers by enabling people to choose their stream. CBS is already committing the resources (cameras, announcers etc) to produce each game, so opening up the streams is a no-brainer.
Because fans are more likely than ever to live outside of their market, other sports should follow the NCAA's lead. For example, Fox could stream the Saturday baseball games of the week, as well as the playoff games that aren't shown live on TV. And every Sunday, there are a dozen NFL games that are NOT shown in each local market.