Chiming in a little late... I'm a less-regular visitor these days because of school and life...
Anecdotally, there are plenty of kids who are interested in cars. In a class this Spring I saw a presentation by a guy in his 20's who buys late model cars that were wrecked and then fixes them up and sells them for a significant profit. Another young guy, just a college senior, is working on his 50's Cadillac in his dad's garage. There are at least 200 students who are in the Auto Restoration program who are interested in pre-70's cars. It might surprise some here to see the number who are interested in pre-war cars. Of course, that's one school in one small town in Kansas, so perhaps not a completely representative sample.
But look on youtube and there are plenty of videos of younger guys wrenching on classic cars or driving them. The 365 Days of A guy wasn't all that much older than me at the time (40). And when I travel to car shows here in mid-Kansas there's a good mix of older guys, younger families, and kids.
The biggest problem, IMO, is the
perceived cost of entry. When you have so many car TV shows focused on the $3 million dollar one-of-a-kind classics, there's a perception that the hobby is just for those with deep pockets. And to some extent that's true: you're not going to find a Model T for $1000 that you can just drive away and then fix up as you have time. But it's not out of reach of people of modest means. The kids I'm going to school with are a case in point: there are a good number who drive a classic to class every day, so they must have afforded them somehow.
Like a lot of old things, there is interest out there. Likely enough interest to keep the hobby humming along for the foreseeable future. So don't fret...
