I thought this is where these two threads were going:
but no one explicitly stated it in those threads, so I’ve created a new one to say that, after playing Thimbleweed Park, it’s very “clear” to me what Ron had planned for SOMI3:
The same fourth-wall breaking ending that Thimbleweed Park has!
Well, I imagine it has “voodoo” instead of “tube-AI”, but that the general gist would be the same. I imagine MI3 would start piratey/theme-parky and the ending would reveal the secret as something like “we only exist in a game! The secret of Monkey Island™ is that it can only be found in an adventure game” etc, and that the player, as Guybrush, would have to thwart @RonGilbert’s plans to continually restart the game, or whatever.
MI1 and 2 already broke the fourth wall a lot: Guybrush talking to the “camera” was a running theme through the whole game, there were a lot of anachronistic objects and speech, the entire MI2 ending. I imagine those LucasArts kidders were just “preparing” you for the ending in a “see, we warned you about this!” kind of way.
And, if this is the ending/theme Ron was thinking of, then, as he says himself:
it really is a really dumb idea