Such a strategy would have its challenges. Aereo's current model has been allowed because it actually assigns a tiny antenna to each customer and keeps them in a separate location. As David Bank, an analyst at RBC Capital Markets, points out, cable companies might need to install new set-top boxes and additional customer service support. Such investments could add up if a cable company wanted to reach millions of customers.
Even if that were a viable threat, broadcast networks have an equally powerful option: converting to pay-TV channels. Both CBS CEO Leslie Moonves and 21st Century Fox COO Chase Carey have said they could switch their flagship broadcast networks to pay TV channels in order to be paid for their content. CBS and 21st Century Fox declined to comment for this story.
Of course, such a move also would have its costs. Switching off the broadcast signal would mean losing some of the several million households that don't have pay TV. And it's unclear that there would be a role for local broadcast affiliates if the networks began selling content in the form of national cable channels.
Ultimately, it seems unlikely either cable companies or broadcasters will be eager to overhaul the TV industry. That means there is little reason to expect less revenue from retransmission, even several years down the road.
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For CBS, retransmission fees and other fixed payments will become even more important over the next couple of years. Such income is generally considered more attractive to investors than advertising revenue because it's less volatile. With CBS set to complete the split-off of its outdoor division, advertising revenue is expected to fall to 50 percent of the total by 2017, down from the current level of 61 percent, according to Anthony DiClemente, an analyst with Nomura.
What should CBS investors expect when the court ruling arrives? Clearly, it would be better for the company to see the Aereo problem go away entirely. A victory for the start-up would create more uncertainty that would likely send the stock a bit lower. But for those with an eye on the long game, any weakness should be read as opportunity.
—By CNBC's John Jannarone