Jim Parsons, Kaley Cuoco-Sweeting and Johnny Galecki Jim Parsons, Kaley Cuoco-Sweeting and Johnny Galecki

The new deals for The Big Bang Theory's Jim Parsons, Johnny Galecki, and Kaley Cuoco, which pay each $1 million per episode, make them the top-earning actors in TV Guide Magazine's annual survey of stars' salaries. But will the trio be the last to reach that seven-figure milestone?

We put the question to many of the network and studio executives and talent agents we query every year to gather the data. All are trying to make sense of how the slicing and dicing of the mass audience — now more fragmented than ever by the rise of online streaming, DVR playback, and video on demand — is changing their business. Series with just a quarter of the 20 million viewers Big Bang averaged last season are being heralded as hits and getting renewed. One network entertainment chief, asked to explain why the show was so much bigger than any other sitcom, says Big Bang, now going into its eighth season, is from "the pre-DVR era," when shows had less competition.

Yet no one says it is impossible for another Big Bang-size hit, one that commands seven-figure paydays for its leads, to come along. "We have to believe that we can do it again," says one TV comedy executive.

But for the actors to cash in, a number of factors would have to fall into place as perfectly as they did for Big Bang. "It has to be a huge, broad, wildly profitable show that is showing no signs of slowing down," says another studio executive, who notes that reaching eight seasons is rare in itself. "It also has to have a small, core cast that has been there from the beginning. The show can't have 11 series regulars, like Modern Family." Nor, the executive notes, can it be a series with a lot of "cast churn." Killing off major characters — a common practice, thanks to Game of Thrones and The Walking Dead — has become an effective way to keep salaries in line on shows with large ensemble casts.

But the rules of the game are rapidly changing, which leads another veteran executive to suggest a streaming TV service such as Netflix could be the next company to sign a $1 million paycheck for the star of one of its original series. Netflix is nearly halfway there with what it pays House of Cards star Kevin Spacey, according to the estimates of industry insiders.

The proliferation of digital scripted shows — thanks to the ramp-up of original TV production by companies like Yahoo, Hulu, and Amazon — is increasing the demand for actors. That could eventually lift their pay after years of studios and networks holding the line on talent costs. (The top starting salary for a network show is $125,000 per episode. The highest figure for cable-show leads is typically $75,000.) "[Amazon] pays really well," says Amy Landecker, costar of the online giant's new comedy Transparent. "You'd be amazed."

Also amazing: American Idol judge Jennifer Lopez will pull in $17.5 million in the show's next cycle, despite the singing competition's staggering ratings drop last season. She'll also work fewer hours. Sometimes the rich just get richer.

For more numbers, check out TV Guide Magazine's 2014 salary roundup photo gallery here.

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