I have no crystal ball, but I think that is apples and oranges. Locally and regionally, stock car racing has been on the decline for years, as well as interest in all things NASCAR post-Dale Sr.
NASCAR has been advancing political correctness enough that a lot of people are not going to need much of a shove to find another outlet for their time and money. It is one thing to serve up a steaming plate of 24/7 Danica Patrick, quite another to do what they are doing now.
Maybe, and I honestly don't follow NASCAR enough to know. But many were indicating that the NFL was losing audience too, and that the younger crowd just wasn't as interested in the sport as past generations were. And that might end up being the case with the NFL, that last season was a blip on the screen before fan interest started back on the downward spiral.