But I bet TV will still be a major thing, say, 30 years in the future. Right now 75% of households in the US pay for TV, so I think your comment is a little overblown.
Over Christmas/New Years I was at my parents place, and they have DirectTV. The first few days were nice. After that I realized I was just watching for the sake of watching just to see what came on next, and it was all reruns of stuff I've already seen.
I am a big fan of curation, but I much prefer the curation of seeing what the programmers put on in prime time and then watching it on demand, or Netflix's recommendations.
If for some reason they couldn't do that, why would 5G change anything?
Perhaps you should meet more people?
(† There aren't 67 million Britons. But TV viewership in the UK is 28.1 million households, and the average household in the UK is 2.4 people, so we end up with an impossible number.)
So that's 12 households you're counting as "TV viewership" that don't watch live TV. They could watch any hypothetical TV show or advertisement, but they in fact will not. They would not disagree with your parent poster.
My mother (retired) is the only person I know who watches live TV. My Facebook is full of people chatting about TV shows (Sabrina, Doctor Who, etc.) but none of them watch it live. Some of them have paid subscriptions to various sources of TV, and many of the same people also have "pirate" hookups to get TV that isn't available in a timely fashion, as described many times they aren't unwilling to pay they're unwilling to be inconvenienced.