While I have nothing but fondness for recollections of CP/M on x80
systems, I've wondered that since memory is cheap, why not resurrect
some of the Unix-cousin attempts? I think Morrow was advertising one
around 1980 and there were others.
I found one here:
http://www.dougbraun.com/uzi.html
It would seem that if the inode arithmetic could be extended to 24 or
32 bits, you could mount filesystems in the GB range. It might be
kind of interesting.
FWIW,
Chuck