Very interesting. If the club ever did something like that my suggestion to them would be to just leave the old 18th green and approach as an optional 18th.
As to the 18th being a real weak link, obviously Robert Hunter didn't think so, as he said this about it:
"The last hole takes us along a very narrow route back to the clubhouse. This hole will require better play than the others and while it is short, it is amazingly difficult and is, perhaps, in its contours and landscape, the most beautiful hole in the world."
On the other hand, I distinctly remember my first reaction when I stood on the 18th tee for the first time. I said to my caddie: "This one sure is odd looking; it looks like they are asking you to hit the tee shot right into a grove of trees."