I've just turned 35 and have a grey hair or two (although I started going bald about 10 years ago, so who knows about what should be on top!), but I guess that I'm around to keep things going.
I know for a fact that one of the guys in my club's daughter, who is in her early 20s, has claimed one of his GPWs and she regularly drives that around.
There is interest, but I guess that a few things that make it hard for younger people are that prices are up, WW2 vehicles are getting very old and, younger people don't tend to have the same sort of car culture as previous generations.
My younger brother is 25 and just about all of his peers see vehicles as a means of transport and nothing more. They aren't into their cars, they are into where their cars can take them, and most of them have no idea how to do even basic maintenance.
Cheers,
Terry