Getting new blood into pinball has been mentioned or asked many times since I've been on pinside, which hasn't been long at all. I'm very new. But I think JohnHarvey has a very apt point when he said

and I couldn't agree more. As a new player (with 0 pins of my own so far), the prices on the market today are the only prices I've known. If prices were to suddenly drop, I'd definitely jump on some pins. But like others have pointed out, it will probably be a gradual decline over a period of years, and I think that's due (in some small part) to having new players that only know current prices, and others that are willing to pay the NIB prices. Not that I think there's anything wrong with buying NIB, but as long the manufacturer can sell them at the prices they are asking, there's no reason for them to decline.