I think the harder the parts become to obtain, the more valuable the vehicles whose owners have successfully managed to keep them on the road and running well will become.
Also, the more NLA's there are, the craftier those of us who want to keep our companions in top nick & driving well will become. Rebuilding water pumps, part substitution or fabrication (as we had to do with the Catalytic Converter for one of my 300SE as they were showing as NLA here in Australia), refurbishment where suitable and eventually straight out cannibalism as the well cared for vehicles become that much more valuable than their poorly maintained brethren that it becomes viable to sacrifice a whole vehicle for a few rare parts.