Sports and entertainment marketers usually plan events assuming the spectators will sit in the seats for 60-90 minutes. That is why there is such a crazy side show going on off the field or track. Go to any event where there are thousands of people and you will find displays and exhibits that might not have anything to do with the particular event. Why do you think the armed services set up elaborate simulators, climbing walls, etc. at races and sporting events?

The fans do not neccessarily leave the stands when the Super Classes run, they would probably get up for the bathroom, food and drink, and visit the sideshow even if they ran 100's of fuel cars all day.

The entry fees from Sportsman racers far exceed the purse money, they aren't going anywhere soon. I don't see T/D and T/S replacing S/C and S/G either, they will replace the alky classes and Comp when they start getting 100 entries for $1000 to win.