I can't see traditional DVB/ATSC surviging much beyond 2040 even accounting for the long tail.
You're right that large scale parallel live streams has only become feasible in the last few years. The BBC has some insights in how the BBC had to change their approach to scale to getting 10 million in 2021, having had technical issues in the 3 million range in 2018
https://www.bbc.co.uk/webarchive/https%3A%2F%2Fwww.bbc.co.uk...
Personally I don't think the latency is solved yet -- TV is slow enough (about 10 seconds from camera to TV), but IP streaming tends to add another 20-40 seconds on top of that.
That's no good when you're watching the penalties. Not only will your neighbours be cheering before you as they watch on normal TV, but even if you're both on the same IPTV you may well 5 seconds of difference.
The total end-to-end time is important too, with 30 seconds the news push notifications, tweets, etc on your phone will come in before you see the result.