Better factor in the make-up of the audience, too. I'm no expert, but it appears that the younger crowd is embracing streaming services while the older crowd tends to stay with what they already know and have already paid for. Meanwhile, the younger crowd doesn't have as much interest in NASCAR (or cars for that matter). Maybe NASCAR expects to overall win more viewers among the younger crowd than it loses among the older crowd... but NASCAR's marketing moves over the past couple of decades have been mostly shooting itself in the foot...
At first I thought a good compromise would be to make races available over the air / regular cable channels simultaneously with streaming services, but then I realized I wouldn't pay extra (use streaming) if I didn't have to, so why would anybody else? This tends to show that streaming services are not cost competitive.
Some industries are able to manipulate and even force their customers to buy and adopt changing technologies over the years... sometimes they can even appeal to those who "keep up with the Joneses"... but those industries usually either sell products that people must buy in order to live, or the changing technologies are cost competitive enough. Sorry, but NASCAR races are not in that category - no matter how big a NASCAR fan one may be, one can live without it. It's only one of a vast array of entertainment choices all vying for your leisure dollars. NASCAR can make all the deals it wants to make races exclusive to streaming services, but it cannot make its customers subscribe. Even the NFL struggles to get fans to buy its streaming - only games, despite whatever numbers are claimed for people using Internet vs. cable services.
Time will tell. For me, I cannot imagine being willing to pay extra to watch NASCAR races. If NASCAR inks new deals that make my only options streaming or pay-per-view, I will entertain myself another way without them.