If they stop making coins, wouldn't that make all existing coins more
valuable from a collector's point of view?
I don't think so, the demise of a mass produced item doesn't
necessarily lead to a great desire on the
part of the public to own them. Collector interest might actually
decrease due to "out of sight out of mind"
I think that the decline of stamp collecting is partly due to fewer
people using them on an everyday basis
to pay bills, send letters etc., which for many is done online these
days.