As the game stands now, I don't think we'd see any AH system like the theme park games have. Why? Because we have no universal currency. Everything right now is barter. Now, there could be an AH system that allows you to place orders. For example, I could post 10 metal blades on the AH with a cost requirement of 100 steel rivets. I think that could work. However, I agree in not wanting AH's run by NPC's.
However, what about a compromise system that actually would help develop trade routes & relationships???
Imagine a Trade Board, where people could post orders like I mentioned above. However, rather than "doing business" at the trade board, bidders would be given directions on who/where to contact if they want to do some business. If I want some saw blades...I can go to the board & see who has some for trade, see what they want for them, & contact that person to begin negotiations. There, of course, would be no mail delivery systems. I think a trade board would be kinda cool & help streamline player interaction.