I agree with you.The only thing that stokes a next generation of loud n proud , football obsessed attendees is an influx of teens and early 20's, but sadly modern football prices that demographic out of the game..... As the arrival of the EPL did to me overnight and for a chunk of the mid 90's.
You see young kids with their parents, but you don't really see groups of teenagers or groups of people in their early 20s. I have only seen a few groups in this age group.
But maybe it has always been the case that people in the their late teens and 20s stop going so much when they discover drink and drugs. But that the higher prices have made going less appealing and less likely.