Ally
In my experience, the Euros have much more willingness to renovate their great old courses than Americans, and I suspect that most if not virtually all courses that have done so would not want to go back to Ye Olden days. Of the courses I know a bit about:
--Dornoch's renovation in 1946 was a massive improvement over what was there before (no, I'm not that old, but all the old holes still exist on the Struie Course, so it is easy to see how the course changed).
--Carnoustie would an inferior course without the 1930-1 renovations. And, the very new New 3rd is significantly better than the old one.
--I doubt that Hoylake or Birkdale or Lahinch or Waterville would like to go back to what they looked like the first time I played them ~1980. The modern improvements are just that--improvements
--Those courses who renovated in response to the Haskell ball and/or a declining tolerance for blindness (e.g. Muirfield, Sandwich, Royal Aberdeen) are unlikely to go back to the old routings.
--even the Old Course was renovated (c. 1850) with the creation of what is now the outward 1/2. Would anybody want to replant the gorse on that land and go back to single file golf down the left hand 1/2 of the course? Well, yes, I know there are people on this site who would but......
Maybe one could restore great lost individual holes such as Sandy Parlour at Deal, but I don't know the course well enough to see how practical that would be. Maybe we can have a field trip whilst at Deal for the BUDA Cup to try to find out!
There actually is one restoration that I think would work, and it is at my home club, Aberdour. About 35 years ago, some land became available and the course was extended from (as I have been told) a superb and extremely compact (60 acres?) par 63 gem with the best greens in Fife to a still charming but less so par 67 with a few long walks between holes and a couple of problematic new greens. When it was in its old routing the Club produced some great golfers, including a British Boys champion, a successful pro, a Curtis Cup player and several winners of the Fife amateur Order of Merit. This from a 4,700 yard course in a village of little more than 1,000 people.
Those must have been the days....
Rich