The world's markets just "run out" of older good stuff. It doesn't disappear it gets collected and leaves the market.

Same thing has happened to Old Master drawings and even late 20th c. Spanish shotguns. Only a few years ago this country was flooded with mid-to-high-quality but very inexpensive Spanish SxSs and that supply seems to have dried up pretty much.

Just means its going to take more money to dislodge some of these guns.