According to this article NFL attendance is down while viewing is up. While the article does not mention specifics about TV ratings, a few teams are called out.
The Cowboys averaged 90,929, leading the league for 11 straight seasons. Fifteen teams saw a decline in attendance, led by the Jaguars (8.7 percent drop), Raiders (7.6 percent) and Bengals (7.0 percent).
Two teams saw an increase of more than five percent. Washington’s audience grew by 7.3 percent (the stadium was still at less than 80 percent capacity), and the Bills have a 6.0-percent jump.
There is always a danger of over interpreting this kind of data point. It could just be noise. A case could also be made that the NFL was doing great in 2004 so this is not a big deal. On the other hand, if the population grows every year (especially in major metros) then attendance should also grow. For example, a quick search suggests that Jacksonville's population has grown by more than 20% since 2000.
The important thing to consider is that the NFL business is about fandom. Fans are incredibly engaged and passionate consumers so even anecdotal evidence of weakening demand should be taken seriously. Fans are the most loyal of consumers. Any softening of demand can be evidence of cracks forming below the surface.