Truer words have never been spoken. As well as a heck of a cool concept. As long as we humans can keep our society, the coins we have will make their way into the hands of others. At some point in time, common
US coins will be like Roman Empire coins - in the hands of the relative few. In reality, the coins are right at the begining stages, since many of the "classic" coins were only really pulled out of circulation within the last 100 years or so. What will happen to them over the next 500 or 1000 years? Who knows? But care-takers, yes. They can't come with us, even if they're buried with us.