For a skiller like myself, someone who despised buying or selling anything because of the complete and utter morons in this game that have ruined it to the point where doing such a simple task is tedious and annoying because they can't seem to read and wind up offering you crap.
This is a blessing and nothing bad can possibly come of it. I don't care if prices go up or down. First thing i'll be doing is dumping up a crap load of stuff I've wanted to sell over the years but couldn't be bothered. Probably slightly over priced just to take advantage of the new system and see how far i can push it.
Then live life happy cause i can quickly and easily buy resources and things that i need with little effort. Providing jagex does this right.
They could mess this right up..but they'd have to be complete idiots to do it. Just let me put items up, let me set the price and then just transfer the money into my bank and notifie me the moment somethings been brought. Easy. Simple. Stress free.
So you don't think the massive autoer population being able to sink all those hundreds of thousands of yews, coal, and lobbies...will have any effect on the game. I can see yews, lobbies, and coal at 50 gp each.
I think there is a very, very real potential for the great exchange to seriously hurt Runescape. With those massive price deflations...you will have people with a few million getting 99 in everything from fm to cooking to smithing...I can see some real harm in that because that is an inflation in stats...that that would make the game very little fun very fast if everyone has 99s.
I don't think it takes as much to screw this up as you thing. Many games like WOW started out with exchanges and have a lot of safeguards against autoers.
Of course as Anubis said it could swing the other way and have more people trying to max out their skills making more demand...but I find with highly unlikely with all the excess resources running around in RS.
I guess we will have to wait and see.
P.S. Did Diablo 2 have a huge problem with crashing economies from autoers?