I would hope we will one day find more of the UNIX emulators that
existed over the years, my list includes:
PRIMIX for PRIME computers running PRIMEOS (had to cope with several
PRIME weirdnesses)
Eunice for VAX/VMS :
https://en.wikipedia.org/wiki/Eunice_(software)
0nix : A Unix emulator for VAX/VMS :
http://www.caam.rice.edu/caam/trs/82/TR82-08.pdf
I find attempts to make other systems behave like Unix fascinating and
the implementations inevitably embellished with interesting and
amusing hackery.
I have a long list of UNIX-hosted programming languages I would like
to find too, but that is wandering off-topic for this list.