Files exist because persistent storage is slow, copying data from RAM to disk is slow and we'd like to have a way to refer by name to blobs of bytes, but in the end it is only there because it's a useful metaphor. If the metaphor gets in the way of our ability to use the storage medium you can either do a mapping (like the direct memory mapping you refer to), which in this case would almost be like a backwards compatibility layer, a more involved scheme where all RAM is backed by persistent storage and devices only keep a flag which objects are currently being worked on and which are stable (an 'open' file would simply be marked as currently in use by an application but there would be no explicit save, just an unlock), or a completely new system based on an image like architecture (see: smalltalk, some lisp implementations). There are some drawbacks to that model (such as harder collaborative development) but I see no reason that applications could not be packaged that way even if the development used a more traditional method.

It would be fairly trivial to layer a conventional filesystem on top of such a persistent object store to get the best of both worlds, which would - amongst others - give you instantaneous suspend and re-awaken and other goodies.

If true this will vastly change the way we use computers.