Local high schools in MN and CO have mtn bike teams that race every week. Racing with the younger generation is not dead, it is thriving - just in a different discipline. Road races are spectacularly expensive and difficult to run compared to other events like fondos, color runs, etc.
IMHO this is USAC's biggest failing over the last 10 years: they haven't changed their approach to supporting (or ahem - ignoring) race promoters. As the race promoters age, and the competition to their events gets stiffer, and USAC continues to turn a blind eye... many of them just give up. The races themselves don't have any value as assets because each promoter is a stand alone small businessman.
If USAC treated race promoters as franchisees (is that a word) I think things would be quite different.
https://www.youtube.com/watch?v=sGRkxBUKCDM

race climb after climb , with a tense review of the 2011 edition
