He didn't say "broadcast TV," but rather "linear TV." Those are not the same. Linear is real time TV. That applies to cable and other things. Appointment viewing is on death row. I agree with that. There are very few things I set my clock for. And even then, if I miss it, there are ways to make it up.
The networks deliver a mass audience. They do it using broadcast and cable. The companies that own them also own hundreds of broadcast TV stations. Those stations are licensed by the government. If big changes start to happen with broadcast, and voters are affected, you can expect Congress to weigh in on the subject. They could require existing networks to continue to provide certain services. There will be someone who will want to access that audience. It might be Sinclair, it might be Nextstar, but there will be someone.
I think he's overstating the situation. People want to get out of the house, especially after three years of covid. The theater owners need to find ways to economize their businesses, because the marketplace has changed. But if they give people a reason to go to theaters, they will go, especially in cities.