What $600 fee?
When revenue goes up a billion dollars in one year you’re not losing clients. At least not in the final math. Sure they’re losing some people, but they’re being replaced. Like LA, I remember back in the 90s they talked about how a million people a year moved out of LA, and yet the population kept going up. The fact of the matter is the NFL (and the entertainment landscape as a whole) is a complex business. TV is losing audience, but that doesn’t mean individual items are losing audience. The NFL has multiple streaming contracts and all the networks have some form of streaming. Then you’ve got all the merch and the international market. It’s very easy for the TV ratings to drop and still get a net gain on audience and revenue. TV ratings have been a postdated measurement for over a decade, adding streaming into the modern just makes them even more postdated.
The source you posted requires a subscription for anything but a summary of major league sports total revenues, and that listed is for 2015 not last or this year. So you still need to back up your claim of rising revenues for the current year.
The only item of interest your source shows outside the pay wall is that in 2015 “regular season ticketing” was 16.45% of revenue (”gate receipts,” so doesn’t include stadium concessions and other sales that are impacted by attendance). I think we can all agree that those numbers were not going up over past two years and will decline even further next year as season ticket holders don’t renew and teams lower prices to try to incentivize sales.