The top runners will continue to go to the major races (New York, Chicago, Boston) because they can compete with the best runners in the world, there are appear

The top runners will continue to go to the major races (New York, Chicago, Boston) because they can compete with the best runners in the world, there are appearance fees for elite runners, and they offer better exposure for athletes who depend on sponsorship dollars to make a living. As for the US Marathon Championships, America's best marathoners usually skip that race (aside from when it serves as the Olympic Trials) because smaller, less prestigious marathons that pay less prize money are often chosen to serve as the US Championship. Why (relatively) smaller marathons? So that your US champion actually wins the race (like they would at the Twin Cities Marathon) instead of finishing somewhere in the top 5 (but not first) at New York.