Here's who's likely to get hurt as all this plays out.

Cable and satellite TV companies

"Obviously at the forefront are any of the cable providers," says Scanlon. "At some point you'll get to where you don't have a cable connection. You just watch all content from the Web." Satellite TV companies face a similar risk.

With a variety of devices in hand and high-speed Internet access almost everywhere, consumers want to be able to chose when and where they watch video content instead of being tied to broadcasters' schedules.

There's another factor at work: A lot of consumers are overpaying for cable, in the sense that they pay a big monthly bill but watch only a few channels. "You are subsidizing all these other channels," says Eiswert. "It's a bizarre business model that has evolved over time. This doesn't make any sense now, because the technology exists to deliver it differently."

SNL Kagan forecasts cable and satellite subscriber growth won't keep up with the growth in households over the medium term, mainly because more people will switch over to the Internet. But change could come much more quickly, depending on the impact of a new Apple TV. A cool and simple-to-use device could catch fire like the iPhone and the iPad did.

None of the major cable or satellite companies, including Comcast (CMCSA, news), Cablevision Systems (CVC, news), Dish Network (DISH, news), would talk with me about the threat.

In defense of cable, Morningstar analyst Michael Hodel points out that $80 a month, a typical cable TV bill, isn't such a bad deal, considering that the average consumer watches four hours of TV a day. Plus, many people actually like having hundreds of channels to surf, and viewing habits run deep. We crave, for example, the sense of belonging that derives from "water cooler moments" when mass audiences watch huge events like the Super Bowl or the last episode of "Lost" and then talk about them.

"I don't think there's going to be a precipitous drop-off in cable subscriptions that will come about in a year or two," says Hodel.

Even Google TV experts -- also aggressively pioneering Web video consumption -- don't think cable is doomed. "The Web won't completely kill traditional TV," says Rishi Chandra, Google TV director of product management.

Cable companies are fighting back by putting a lot more content online and making it available on demand, giving consumers flexibility. Comcast's Xfinity TV offers hundreds of thousands of movies and TV shows online. Comcast just inked a deal with Walt Disney (DIS, news)that moves ESPN, ABC and Disney shows online and on demand.

But can they keep up? The other megatrend playing out here is the growing availability of a nearly unlimited choice of video content online, including specialized niche programming at places like YouTube.

Google's Chandra puts it this way: Video content has morphed from three channels in the early days of TV, to 300 channels with the advent of cable, to 3 million channels with the rise of the Internet. Google is promoting the trend by rolling out YouTube channels, putting a Google TV operating system on a lot of popular TVs and helping consumers find things through search.

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Of course, a lot of consumers get their Internet service along with cable. So, as we convert to Web-based TV and video in a big way, expect cable companies to raise prices for Internet service to offset cable subscriber losses. "I suspect they are not going to spend a lot to be the backbone for delivering high-bandwidth use and not charge more for it," says Michael Sansoterra, portfolio manager of the RidgeWorth Large Cap Growth (STCAX)fund, which has beaten competing funds by an annualized 1.5% over the past five years.