I raced Formula Vee from 2008 up to a few years ago with SOVREN. The bigger money guys like Bruce McCaw have retired or only go to bigger money events these days. Some of these teams could bring 10-20 cars to an event. I haven't seen the Emory's there in years. In some ways, vintage has been the victim of it's own success. Events competing with other events. Car values have had an impact as well.
A few deaths at events in recent years, Chuck Lyford in Spokane and recently Jim Bushnell in a 911 in April at
PR have probably had an impact.
They have tried to expand membership by letting newer cars in. They waited way to long to do that.
I have been prepping a 914 and did Portland last labor day but having type 1 diabetes has me looking at retiring. Too much risk of having a low blood sugar event in the car and life has changed so much since 2008. I got remarried, now have 3 grandkids fairly close. Life priorities have shifted. I miss it but "it" had become a lot less over the last several years.
I think in many ways vintage racing mirrors where the classic car hobby is going. It was always an old guys game and those old guys have or are aging out and not being replaced.