To be honest, I really feel that interest of marching music in America is on the decline.
Yes, WGI is thriving with winterguards and more and more winter drumlines. However, the average marching band, atleast in Indiana is shrinking. Whereas in the smaller classes there would be 80-100 in a band, there are MANY bands with only 40-50 total. Even the larger bands that packed 300+ are down in the mid to low 200's.
The same has happened with drum corps. The death of many smaller corps has built a disconnect between the average person and the drum corps community. There might be 1 or 2 drum corps in a state now that used to have one for each region or community.
Something needs to happen to keep this alive, or I see this activity start to fizzle out completely. With rising costs for arrangers, drill writers, copyrights... It's just not worth the investment at some point.