In the past, that has meant that the older models (which remain available) drop sharply in price: to $0 if you are willing to sign a 2-year contract, sometimes.
Whether the rumor is accurate or not, retailers have started dropping the price of the iPhone 4S.
For you as an iPhone carrying pawn customer, what this means is that you will not be able to borrow as much on your phone from now on.
Smartphones are a very popular pawn item. It must be hard to part with your phone, but, hey, sometimes you gotta get a bridge loan to eat or pay rent.