You'd probably still have memory partitioned into persistent areas and runtime heap of a sort, and you might very well continue to use the file system metaphor because it still makes sense to humans. Whether a file is bits on magnetic disk, in flash memory, or fast persistent RAM isn't all that meaningful to the user. As for sharing, I don't see why this would be an issue. If you have to move memory contents between machines then you still need some sort of external transport, whether it is a network, or a glowing glass cube.