In fact, we still call them Manila folders - but everyone's forgotten that the "Manila" part of the name comes from the fact that they were made from Manila hemp, a fiber produced in the Philippines.
Language is made of these kinds of artifacts - written, spoken, and visual language.
It's pretty common for the original meaning of symbols to disappear into the mists of time. Using a floppy for 'save' seems like a good one to add to humanity's set of 21st Century pictographs.
If you put the chisel diagonal and hit it with a hammer right off the bat, it just slides across the stone, and you usually hurt your thumb ;)
With the move towards Flash SSDs, even this is going to become quaint. If Apple keeps going the direction it is now, OS X or its successor is going to have orthogonal persistence cached on local SSDs and replicated in the cloud. Eventually, no one is going to even think about saving things anymore.