As you know, I believe, in hindsight, that the regular Auction House in Diablo 3 is a mistake. There have been several comments by the dev team that indicate that they are leaning to this view as well. Not to mention the crazy inflation due to recent bugs.
Assuming that the dev team comes to the same conclusion, here's a question:
Should D3 remove the auction house in the inevitable expansion?
Now, obviously if the AH is a mistake, the game without the AH would be a better game. But on the other hand, the people who are still playing Diablo 3 are okay with the Auction House. A significant number of them like it. (Some may be playing in spite of it.)
I think this is one of the hardest questions for MMOs and persistent games. Should you remove a feature that your current playerbase likes, if you think that it will lead to a better game and/or more subscribers? After all, as the saying goes, a bird in the hand is worth two in the bush.
As well, if you can't remove a feature, does that make you less likely to add new features, realizing that you can't go back if they prove to be a mistake?
Perhaps for D3 specifically, the best idea would be to introduce a new "No-Market" game mode. Like Hardcore, characters in that mode would not share a stash with characters in other modes. And that mode cannot access the Auction House or trade items. But gameplay would be the same as Normal.
It will be interesting to see how Blizzard approaches the Auction House in the new expansion.