That really depends. Eventually the deceased player autographs will work their way into collections and the supply dries up. Then buyers will take what they can get and higher prices than before. There will always be a few floating around in the market at any given time, but not as many as now.
It also depends on the type of card. Those cheesy Pacific Legends, Swell and other cheap collectors issue cards don't have nearly the value as a nice vintage or better card. The exception there is those who have transcended card type, like a Williams, DiMaggio, Mantle type that sell for big $$ no matter what you find signed.
In the case of Puckett specifically, now: He is recently deceased but didn't seem to have an overwhelming number of certified autos. The demand will remain strong for his pack certified cards, but the IP/TTM autos will slowly gain ground. He also didn't play far enough ago to have sweet vintage cards, so the best you can hope to find signed are his minor league issues, his 84 Fleer traded and perhaps his T/F/D rookie cards to a lesser extent. I have seen a fairly large difference in autograph styles too, making it hard to really feel good about his signature on anything uncertified!
