There are probably tens of thousands of 1952 Topps Mantle cards surviving for several reasons:
1.) He was double-printed sheets of 1952 Topps high numbers
2.) His card was saved more because he was already one of the most popular players in New York.
3.) Unlike tobacco cards, modern bubble gum cards were saved at a far greater rate.
Just this past auction period (2 months) we had three 1952 Topps Mantle cards consigned to us, all ungraded. We then submitted them to PSA for our consignors. I've handled probably 25 raw 1952 Topps Mantle cards. By far, there are thousands of more 1952 Topps Mantle cards just waiting to be discovered....most of them in the hands of non-collectors.