Yes, I've considered "The End" of old coins scenario. In fact I've witnessed it. The hayday of finding silver in large quantities is definitely over. The first detectors beginning about 20 years ago sucked most of those coins out. The school I attended in 1950 is devoid of silver. I lost many coins there as a child. Every one was silver. Many nickles I lost were Indian Heads. There are undoubtadly a few left, but your gonna have to work many hours to find em. I even know the name of the early detectorist who cleaned that school out beginning about 20 years ago.

In addition, many older areas are rapidly being paved over. I kinda feel sorry for kids these days. When I was a youngster, we had lots of open fields to play in. Today, as I drive around, I don't see any empty lots. If I do, they are fenced and posted until they are built on or turned into a parking lot. This is in the metropolitan area I currently live in. Many areas of the Southwest and Midwest haven't seen a detector yet. I lived in Tucamcari NM for a little over a year and that area has a lot of really old sites that haven't ever seen a detector. It's a big country. Lot of ground to search.

As far as catch and release is concerned, there are a small number of MDers who are purposely planting clads in obscure areas so future MDers will have some coins to find.

How many years will a clad quarter last before disolving or becoming unrecognizable as a coin grass hopper?