Relative to the number of titles, 4K makes up a rather small portion of what's currently available. The premium movie channels offer some of their exclusive content in 4K but most isn't. Same with Amazon Prime and Netflix. The percentage is very low.
Sports-wise, the 4K options are knife-edge thin. The broadcast TV networks haven't taken to 4K in any meaningful way.
Unless all you watch is blockbuster movies and "original programming" streaming content, 4K is most certainly not available by the ton.
You are correct as far as Traditional Providers go, which the Premium Movie, Broadcast, cable and sports channels are part of, and those channels are slowly dying and ratings are getting less and less a year.
Providers themselves have less and less customers, Dish Satellite Network just a few years ago had roughly 14 million subs, now in the 8 million range, at the rate DirecTV is going, they will not have anyone left in a few years.
Now as far as content in 4K and Netflix goes, the vast majority of their
new programming ( and there is a lot of it) is in 4K and has been for more then 8 years, it is obvious they find value to broadcast in 4K and that is part of why their sub numbers are so good,
Heck in their short lifecycle of doing video over the net, they have more subs then HBO, both in the US and worldwide and HBO has been in business more then 40 years.
HBO US-36.3 million
HBO Worldwide-138 million
Netflix US-65 million
NETFLIX Worldwide-190 million
Prime is a little different, while all their new content is in 4K, there is not much of it, they premiere about 2 new seasons a month of 4K, of either new or returning shows, I would think the majority of people who have Prime is because of the shipping, myself included, been great for us during our move.
While Prime does not have a lot in 4K, it is still more then every Traditional Broadcast, Cable, News, Sports Channels combined.