Just pretend the floppy disk never existed, and that the floppy-save symbol is just a completely abstract symbol. Doesn't it still work? As long as a symbol is unique, easy to identify, and easy to reproduce, it does its job. I'd argue that floppy symbol has stuck around because, on a purely visual level, it's hard to beat.
If one take the idea of saving outside the computing world (meaning where the computer is used on a daily basis), then I see two choices for the representation: a bank safe as the old age mean to save (money or valuable in this case) or a folder for document (dead tree medium are not going to die any time soon). I think that a study needs to be done among non computing educated people to understand better what is their mental (pictural) representation of the action of saving is.
All I am saying is that the floppy disk is pretty much a cultural centric representation of the action of saving valuable information for later retrieval.
Surely one could make the same arguments about bank safes and paper folders, to a certain extent?
Any replacement for the floppy would need to be immediately recognisable and not already tied symbolically to another concept. My argument, simply, is that I don't think there's anything better. The floppy is a unique shape and conceptually tied only to "saving". The effort required to move away from a commonly-used symbol isn't trivial and I just don't think there's much to be gained.