I have studied the coin market and its history for many years. All across the board, hobbies are changing. Kids do not build models anymore, crafts are a fraction of what they were 20 years ago, and I have no idea if there is a single shop in New Hampshire specializing in sports cards. In the early 1960s Chet Krause estimated there were 6,000 coin shops in the USA (every small town had one, large cities had a page of listings in the Yellow Pages), and so on.

I agree that collecting stuff (and hobbies in general) are on the decline, but that may change as the younger generation becomes more prosperous (assuming they do at some point). Young people are burdened with student loans and low paying jobs that keep them in small apartments well into their thirties. They aren't benefitting from the prosperity we knew as kids and young adults.

There does still exist some collecting interest in young people, but it may be of a more utilitarian nature. My ladyfriend's teenage boys actively collect Yu-Gi-Oh! cards, but then they actually play a game with them. The cards are prized and stored inside plastic sleeves, but they're not mounted in an album for display or submitted for grading.

Most of the new adherents to coin collecting in recent years have discovered this hobby as adults, oftentimes as a by-product of investing in bullion. I don't believe we'll ever again see coin collecting as the massive fad it became in the early 1960s, and the hobby may regain the smaller scale it had before the era of coin boards and folders. This is not a good sign for the large numbers of common coins that have survived, and it's doubtful that many persons will be just "filling the holes" with circulated Buffalos and Mercuries, but there should always be enough participants to support a market for choice and truly scarce coins.