But that's the risk with all coins. They could open an old vault tomorrow and find bags will of gem BU 1893-S Morgan Dollars and the value of that coin would plummet. That's the risk of this hobby...and it has happened before.
But the difference is the Morgan MIGHT HAVE that scenario happen. The quarters ALREADY HAVE that scenario in existance. The quarters don't need an old vault to open, the mint emptied a shipping department full of them, to just about everybody. However, I have beat this horse to death and will leave it alone and let it get some rest.
That is true. However, there is nothing wrong with looking for varieties and enjoying the hunt. Plus, if you find one it is worth something NOW if you decide to sell it. If you are searching through circulated coins...what is the hurt, you only have face value in the coin.