What the networks pay the NFL is already determined. Even if viewership drops the NFL still gets paid.
From this article: [
www.investopedia.com]
The NFL currently has TV deals with CBS, NBC (owned by Comcast), Fox, and ESPN (owned by Disney/Hearst). In contracts that were finalized in 2011, CBS, NBC, and Fox committed to pay the NFL a total of $39.6 billion between the 2014 and 2022 seasons. The three broadcasters share rights to "Sunday Night Football,” as well as annually rotating rights to the Super Bowl. Fees paid by these networks are set to rise about 7% annually, meaning they will each be paying the NFL about $3.1 billion per year by 2022.
In the same year, ESPN signed a deal to pay the NFL $15.2 billion through 2021 for the rights to “Monday Night Football.”
In 2018, Fox signed an additional deal for $3.3 billion for exclusive rights to “Thursday Night Football,” outbidding NBC and CBS.
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