That marketplace is going to push prices through the floor, uber deflation lol. My bet is on rune going down to bou 6-7k a bar, rune wc axe going right down to 10k, and rares rising consistently as they become incredibly easy to sell. I can see runescape putting the selling prices to shops up to try and halt the deflation. The big update will probably either be a radical change to the combat system, a radical change to the graphics, a complete rework of the bank system, or a incredible new skill a fair bit bigger than construction. And yeah I think we could see a price fixing merchants guild coming along very very soon.