I foresee this happening as well, but it depends on the fees and what other limits blizzard puts on the real money auction house.

However, to make the real money auction house competitive with the type of websites that blizzard is trying to close down on this idea, they can't give it too many limitations. So I don't really see how they will truly prevent the "real" currency of the game being real money

I'd have to concur here, there's certainly incentive for using the gold-based auction house if you're a buyer, but when selling items, which are you going to choose?

Of course, now that I think about it, you can use gold you make from the gold-based auction house and then turn it around to make a tidy profit on the cash-based one, so it -might- work once the market stabilizes.

That being said, I'm more tiffed about the fact that there's no offline play for diablo 3, but I digress.

I wouldn't worry about it too much. Say that this happens, and the gold AH ends up like WoW's neutral AH. (ie. Mostly empty.)

With the option to sell items for a cash balance on your Battle.net account, and then buy gold from people on the cash AH, you've simply changed

Items > Gold

into

Items > Cash balance > Gold

The economy fluctuates a little more, but anyone who simply wants to sell their stuff to get gold only has one more step to bounce through, with the end result being the same.

Additionally, in your scenario the people using the market to convert gold to cash are no different from how they are today, save that there are consequences for abusing the system. Item doesn't sell? You just lost your cash deposit. Someone undercuts you because you priced too high? You can buy it out (and risk having more unsold inventory) or leave it (and risk having yours not sell as the market drops.)

It's not going to change the so-called gray market OR the in-game economy significantly. The change is that savvy people will sell their gold and items to earn a cash balance that their subscription is paid from, gray-market transactions will be less attractive (because a matching equivalent in-game is safer)... and stolen credit cards will be much trickier, as Blizzard can use a verification process to control who can cash out.

Well, I don't think that people will be posting vast quantities of valueless stuff. One thing that I didn't see in this write up of the auction system is that Blizz is setting up a multi-teared fee system. First they have a cut based on wheather or not the item was sold, and then a second cut after sale, based on how much it sold for. Second, they will allow a small amount of free transactions over a given time, but the more auctions posted, then a fee will be applied to each item you post.

Also, if you want real money for your transactions, you have to register your battle.net account with a third party system (e.g. paypal) and you must accept their transaction fees as well. I am not saying that this will eliminate people trying to make a business based off of selling in-game currency/items, but these restrictions will favore those who use the auction house more casually.

In other words, if I were to sell two or three items in a day, my overhead due to blizzard's cut is less than the guy that tries to sell 30 items. While he might make more money over-all, if he doesn't sell, he takes a much larger hit.

In the short term will "gold farmers" buy up things and attempt to make a profit? Sure. But in the long term blizzard will shut them down hard. The reason why gold farmers can make the large profits is because the initial transactions are handled on their own websites.

With blizzard doing things in house they can easily freeze all assets in the b.net account and/or any connected paypal like accounts. When you are the one providing the service, you have an even greater control over who uses it and for what purpose.

It doesn't really matter, since you can also buy and sell gold for real money in the auction house. I'm not sure how easy it will be to get gold in Diablo3 (if killing a mob drops gold or not), but I expect that gold will be so de-valued to be practically worthless, because who would want gold when they can sell their loot for dollars instead?

At any rate, it's genius, as an example of "If you can't beat them, join them". As long as "Chinese gold farmers" (I hate that term) are making transactions through the Auction House, Blizzard gets a cut.