I think we should just keep the floppy disk symbol at this point, because it doesn't matter what it was originally based on or whether that exists any more--everyone knows what that symbol means, and it can't really be confused with anything else.

There's no point making an icon that looks like any other particular kind of storage device since those are changing all the time. So we either have to pick some real world thing like a safe or warehouse or grain silo or whatever. or invent some completely new symbol that's not related to anything and then everyone would have to learn it. Which takes us back to just keeping the floppy disk symbol.