Perhaps an indirect method of limiting the supply of pilots would be to raise the minimum experience level for instructors.
Read an interesting article by Steve Tizzard who (amongst other things) advocated a minimum experience level of about 1,000 hours before being eligible for an instructor rating.
Would provide a smaller pool of more experienced instructors, and therefore a reduced (but hopefully better taught) output of student pilots.
Who knows - perhaps then the law of supply and demand would work in our favour?