It's success is guaranteed by the net's very makeup - the net is simply too good at gathering communities of interest, too good at freely distributing content, and too lousy at keeping anything locked inside subscription networks, for it to fail. Like TV, the net is better at getting people to pay attention than anything else. Its a question of scale and time horizons. One of the reasons for the skepticism about applying the TV model to the Internet is the enormous gulf between the two media. This is reflected in both the relative sizes of their audiences and the incomes of those businesses - TV is the quintessential mass medium, commanding tens of millions more viewers than the net does.
TV dwarfs the net in both popularity and income.
Many people have written about the differences between the net and television, usually focussing on the difference between broadcast models and packet switched models like multicasting and narrowcasting, but these analyses, while important, overlook one of the principal differences between the two media. The thing that turned TV into the behemoth we know today isn't broadcast technology but scarcity. Because the airwaves were deemed a public good, their use was heavily regulated by the FCC, and as a consequence only three companies got to play on a national level. It is difficult to overstate the effect this had on the medium. With just three players, a TV show of merely average popularity would get a third of the available audience, so all the networks were locked in a decades long three-way race for the attention of the 'average' viewer.