In the immediate future, the ACCN revenue will go up. The per subscriber rates just went up in the #5 and #10 media markets. The three new teams just increased the revenue by somewhere around $60 million per year.
In 20 years, direct streaming of sports will probably be greater than linear stations. However, there have been predictions for 10-15 years that linear cable would be out of business within 5 years. It has declined, but hasn't gone away. ESPN still makes the majority of their income from linear TV subscribers. Streaming/internet income is still a very small fraction of their revenue. ESPN is in a catch 22 position. They know that long term, 20-30 years, they can't depend on linear TV subscriptions. However, they can't go all in on streaming because they would immediately lose 60-70% of their revenue. The cable companies are pushing to have the internet and streaming content included in the subscription costs to their customers. (They are asking if their subscribers are paying $15-18 per month for all of the ESPN stations, why should they be locked out of a $5-7 subscription for sports news stories?) Things are changing. Things will change. But it will take many years or a few decades instead of only a few years. ESPN will probably still be making a majority of their revenue from linear TV subscriptions when the ACC contract ends in 2036. There is no reason for them to turn down a few hundred million per year during that time.