You can't predict the future, just because they haven't been found yet, it doesn't mean they won't be found in the future. If the antiquarians of the 18th and 19th centuries had had metal detectors, there would be little for us to find now, and the same goes for the future as of now. We must save some finds for the future. I don't want a sterilized earth in 50 years time........I might wish to become a metal detcector in my dotage...