With the 2009 Sprint Nextel (NYSE:S) cup series approaching, many predict that NASCAR's upcoming season will be one of the least certain in its history. That uncertainty is both contagious and directly relevant to International Speedway Corporation's (NASDAQ:ISCA) long-term prospects.

ISC's sales fell in its fourth quarter, and its future outlook seemed equally grim. The company earned $0.69 per share on $205.3 million in revenue, which fell 19%. But ISC expects next year's bottom line to land between $2.35 and $2.45 a share -- compared with last year's $2.71.

In this economic environment, that sort of decline isn't surprising. But in the longer term, ISC's success will rely on the continuing popularity of stock car racing -- specifically NASCAR.

On that front, the news isn't encouraging. NASCAR has already lost a handful of sponsorships, most notably Home Depot (NYSE:HD), which had been its official home-improvement warehouse for the last decade. Given cost-cutting measures under way at several companies that are highly visible in the world of stock-car racing -- including Ford (NYSE:F), GM (NYSE:GM), and Caterpillar (NYSE:CAT) -- Home Depot's move could just be the beginning.

The impact on ISC
NASCAR's loss of sponsorship funding could adversely affect ISC. ISC has an almost symbotic relationship with NASCAR, relying on the league for a large chunk of its racing revenue. If it can't replace lost sponsorships, NASCAR will lose money that could be spent on promotions --- the kind of marketing that helped grow its fan base and bring paying customers into racetracks over the last decade.

Even without the economic crisis, ISC could still be in trouble, because of waning interest in racing. In recent years, NASCAR promoters have gone to great lengths to attract new fans. Some believe that in doing so, they've neglected their core audience of die-hard NASCAR fans. If enough poseurs lose interest during these difficult times, NASCAR will suffer. In that case, ISC shareholders should expect to see more empty seats this season.

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Fool contributor Chris Jones owns shares of Caterpillar. He also believes that NASCAR isn't just a sport … it's racing! Sprint Nextel and Home Depot are Motley Fool Inside Value selections. Try any of our Foolish newsletter services free for 30 days. The Motley Fool's disclosure policy won't put you into the wall (unless you're Mike Wallace).