Analysts predict 5G could disrupt the cable business.

Wireless carriers, like Verizon and T-Mobile, could convert customers at Comcast and Charter to their fixed wireless home broadband service.

The analysts sketched out a "worst case" scenario where Verizon and T-Mobile could eat into 11.6% of the cable industry's broadband business by 2024.

The threat that 5G poses to the cable business is so ominous that industry analysts are trying to handicap just how many people will cut the cord as a result.

Specifically, some analysts are already taking guesses as to how many customers will bail on cable giants like Comcast and Charter if wireless carriers moving into fixed home broadband as expected.

And the early estimates of how many homes at risk are in the millions.

Cable companies provide fixed line broadband to homes, or internet delivered through cables and that connect to a modem. 5G fixed wireless broadband uses radio signals and installation of an antenna outside of the home to deliver internet.

That's scary for cable companies, which have made a killing on wiring people's homes for broadband.

"We see 5G fixed wireless broadband as the largest existential threat to broadband providers, by far," analysts at Cowen wrote in their quarterly cable update. "For now, the largest threats are coming from Verizon and T-Mobile."

Millions of cable customers may soon be up for grabs

The analysts laid out the possible encroachment of Verizon into Comcast and Charter markets by noting Verizon's initial four 5G cities —Houston, Sacramento, Indianapolis, Los Angeles — all seem aimed at disruption. The four cities are all markets where Verizon is not the incumbent carrier, meaning there is room for growth in the market.

Comcast is the cable internet service provider in Houston, Indianapolis, and Sacramento, and Charter is ISP in Los Angeles.

The analysts then drew up an illustrative example, looking at similar markets for disruption around the US and identified places where Verizon has made deep fiber investment and it's not the incumbent. The report estimated that these markets would constitute 33 million households nationwide and determined that Comcast would have 2.1 million homes exposed (or 8.3% of its base) and Charter would have 1.1 million homes exposed (4.7% of its base).

Of course, Verizon wouldn't take 100% of these homes over, so assuming the company had a 25% win rate, it could take about 2.1% of Comcast's customers and 1.2% of Charter's, a limited risk, the report notes.

But the analysts sketched out a "worst case" scenario whereby Verizon and T-Mobile could encroach into 11.6% of the 5G fixed broadband market by 2024.