One interesting thing about the original plan is that Unix was essentially text only back then. Part of the idea of making it more Lisp Machine-like was to have a GUI, so when Unix got that (with X11 eventually winning) this part of the plan became less urgent.
I suppose an Emacs OS would be sort of a GUI but not quite?
The MIT derived Lisp Machines had all an Emacs called Zmacs.
But that was just one application among dozens others. Applications usually were not based on Zmacs, with only a few exceptions: on a Symbolics: Zmail and the Concordia documentation editor application frame. Other tools were not Zmacs based: Listener/REPL, the debugger, the directory editor, the font editor, the PEEK tool to view system details, the document examiner, the tape tool, ...
One interesting thing about the original plan is that Unix was essentially text only back then. Part of the idea of making it more Lisp Machine-like was to have a GUI, so when Unix got that (with X11 eventually winning) this part of the plan became less urgent.
I suppose an Emacs OS would be sort of a GUI but not quite?