No one expected prices to rise as much as they did. Otherwise we all would have bought more points. But one major factor is how does DVD respond with direct prices. People are clearly willing to pay at current prices and with limited resale inventory, I think DVD will raise prices across the board. They already increased prices on sold out resorts, but they could do it again (and with larger increases).
Lets say they increase prices, resale prices typically follow direct price increases at some reduced percent (i.e., 60-70%). So its not unrealistic to think that they may continue to increase