While you are correct that prices on all the morphs will fall, it is their "commonness" that will bring the price down. This doesn't mean that normals will become uncommon, just that the rarer morphs will become more common. Those are two very different things. The morphs will never be as common as normals. (except for possibly the codominants).
Breed an albino to a normal and you get 1/2 normal looking babies. How about a pastel to a normal? Why would the normals or hets. be worth more than albinos or pastels in these cases? There aren't fewer of them. Do you think people will stop breeding pastels to normals in the future, if the price on pastels comes down? Not a chance! Sorry, but that theory make no sense.--Not to mention that there is still a wild population, and assuming their habitat isn't destroyed, they will be available for a long time. (since the demand for them will fall as breeding balls becomes more common, and the collecting pressures on them will also fall which will increase their numbers in the wild long before your captive normals ever become "rare".) And if the price of normals goes way up, I guarantee you that it will be much more worth it to import them than it is today, and they import a lot of them today!
Keep dreaming though! 
Rodney