What is the timeline you are referring to in the world of art appreciation? How valuable were originals worth when sold versus following the death of the artist?
We already saw this several decades ago when Salvador Dali's unscrupulous guardians/executors ran thousands and thousands of lithographs and faked his signature on them. Once the deception was discovered, the price crashed on ALL Dali's prints, not just the fake ones.
The GOOD side to this was that I was able to pick up what is almost certainly a fake Dali print for less than $75 at an art auction (I was the only one who bid on it - and it came with a frame, too!)
But since Kincade's stuff was similarly run off in the thousands and thousands and arbitrarily divided up into "limited editions", its value will not hold, despite original purchasers being duped into paying steep prices. Law of supply and demand is also operating here.
The value of the originals has very little to do with the value of endless prints run off and marketed as limited editions. These prints are individually treated as very valuable, but in reality are barely worth the media used to print them, because there are so many.