On the eve of the "Greatest Day of Motorsports," it's relevant to stop and assess the health of the three racing organizations. NASCAR is booming, experiencing a growth in fan base both overwhelming and unexpected. Once a redneck hobby, NASCAR now has major media coverage for the minor-league (Nationwide and Craftsman Truck) series as well as the big boys. Corporate sponsorship and driver recognition is off the charts. F1 has been the top racing league in Europe and most of the rest of the world for quite some time, and nothing appears ready to change about that. To keep things interesting, McLaren and Ferrari have four young drivers who could establish a decade-long rivalry of the highest caliber (Hamilton, Alonso, Massa, Raikkonen). IRL/CART, on the other hand, is struggling.
The most successful driver to have switched over is Juan Pablo Montoya. However, he's much better than the other open-wheelers. He dominated in his brief time with IRL/CART, setting rookie records and winning the Indy 500. Then he spent some years in F1, doing an outstanding job for a team other than Ferrari. He's in a class above the rest of these guys and it shows.
The merger of IRL and CART has the potential to bring open-wheel racing back to prominence in the US, but it has a long, long way to come. If things don't turn around soon, IRL may be equivalent to ARCA and the other lower-tier racing circuits, and they won't be able to afford the Brickyard.