But are revenues shrinking? The contracts with the networs have 5 and 6 years yet to run, so the NFL won't see a decrease until then. Maybe not even the networks:
The networks point out that they offer make-goods every year, and can do so without hurting their revenue. That’s because NFL ad rates are so high, and there are so many games, that inventory rarely sells out, leaving a cushion of unsold commercial time to make it up to advertisers, one ad buyer said.