Modern MX
At the recent Conondale GP (October 10th) the "Vets" had a full grid.
Of course "Vets" was "over 35"! If I was 36 I'd probably happy (ecstatic!?!), but I'm over 50.
There seemed to be plenty of "older" riders and I think the cut off for "Vets" could be raised a bit, or a second class created.
Modern Supermoto
At the Aussie champs in June, there were plenty of 50+ competitors for a class. An under subscribed 45-50yo class meant they were combined. 45 is still a long way from 35, especially in MX with 20 min motos.
You don't stop riding because you get old. You get old because you stop riding.