#4 The fans
Fans are an important part of any sport and the same is true for NASCAR as well. With that being said, NASCAR has made some very questionable decisions over the few years and it has caused even their most diehard fans to leave in droves. Furthermore, the decisions have also left a harsh divide among the remaining fans, which hasn't helped things.
Unfortunately for NASCAR, that divide remains wider than ever and has caused a lot of infighting among the fandom. For example, while younger fans appreciate the round system of the playoffs and the heads up final four during championship weekend, older fans see it as manufactured excitement and disrespectful to the sports original legacy.
Another example is the segment racing, which is also something that has gotten mixed reviews. Of course, NASCAR's probably not going to change that aspect of the racing product, especially since it has been growing on fans for years now, but it's still something that angers the older fan base.
In the end, infighting is a big problem when it comes to NASCAR fans and it's hard to decide where things will go from here. It would be easier if the fans could all just agree on where NASCAR goes next, but since there is such a divide in what each side thinks the sport should be, it may never find solid footing again.