See I think this whole thing depends on how quickly a new design would take over. Because today, 60 something years after the mercury dime was changed. Let's say that they are about 1 in 10000 to find in circulation. Just for easy math. That means about 60 years after they change from roosevelt we'll see about 1 in 10000 roosevelts. Now today let's say that finding a silver roosevelt is about 1 in 1000, again for easy math. So if in 60 years a roosevelt is 1 in 10000 and out of 1000 roosevelts you find 1 silver one that would mean that the odds of finding a silver dime are about 1 in 10,000,000, or 1 in 4000 searched boxes, obviously not worth it. Since the designs which are currently in circulation are also the last ones to have silver, silver hunting won't last long after a redesign. but odds are we'll be hunting for clads sometime in the near future as well. It's all yet to be determined