The U.S. Government did away with the 90% silver (.900 fine) quarters (and dimes and half dollars) in 1964 because there was more than .25 cents worth of melt value silver in each .25 cent coin. This is why $1 silver dollars by the $1000 bag were disappearing from the casinos at such a rapid rate and the Nevada State law (the largest silver producing state in the country) had to be changed to permit $1 tokens to be made by the Franklin Mint in place of the silver dollar to accomodate the casino industry.

There is only .6 of an ounce of .999 fine silver in the present $10 silver strike, which is not at melt value (yet).

However, there is another potential option to your speculative scenario ... which has already happened in my opinion. That is; the casinos make it increasingly harder for players to win a silver strike. I believe that current strikes are harder to win on todays silver strike machines than it was with the older (original) silver strike machines with the single bar, double bar, triple bar payouts.

So, even if silver goes to $20 per ounce ... and the strike machines are set to pay out even less frequently than they are now ... they will still make a profit for the house. In addition, twenty harder-to-win $10 strikes to cash in exchange for a $200 one-pounder means that the $200 strike costs more to win as well.