Last night when I first heard about the new "Remote AH service" that would be available as a premium subscription (an extra $3 a month) I had a small knee-jerk reaction that Blizzard had finally done it. I thought for sure that unlike a non-combat pet or BoA mount, they'd finally offered a paid service to give you an advantage (in game) over non paying players.
I think I was wrong
First, I will admit that playing the AH is definitely a game. Take a look at all the gold-making sites on the internet, and you'll see that playing the AH is definately a game within the game of WoW. There is an entire sub-culture of AH grinders and prospectors. Addons have been developed solely for the purpose of helping you buy low and sell high. Trend watching, securing farmers (for mats), and speculation are the order of the day for these players. The Gold Cap is their Lich King, and they're grinding away to get there.
Much like twinks however, these players aren't playing the developers vision of WoW - so they aren't really supported. They aren't being entirely shunted off to the side either, but they aren't the developer's target audience.
First, the paid service will be limited to 200 transactions per day. Even with the built in ability to batch post stacks now, I think the 200 transaction limiter will be a ceiling for real AH workers. Plus there's no ability to work your professions with this application - so you can't cut gems, mill herbs, scribe, etc. You're stuck with working with what's in your current inventories.
Second, not having the functionality of Auctioneer to do scanning, price adjustments, etc. will definitely hurt the AH playing crowd. It's simply not as advanced a tool as they are used to using.
I'm going to sign in and use the Beta when I get home, but here's one 'issue' I can see - or maybe it's the real benifit. Right now (as an Engineer) I can access my bank and my mail from anywhere in the world at the drop of a hat. There has been more than one occasion where our raid needed something from the AH, so I'd log onto an alt in Org - purchase it and mail it to myself. Can I now skip this step by running the app on a second monitor?
Rage> Dang it I need a leg kit so I can make use of my 4-pc tanking bonus for H LK. You know, because he hits like a truck.
Me> Here you go.
Rage> You're not a leatherworker!
Me> Nope, I've just got more disposable income.
If you don't have to be logged out (or even in) a city with an AH that you can access - then I see this becoming used more by farmers and/or raiders than by the real AH players. If I can just open up a browser to empty my bags from anywhere in the world - that will cut down on having to hit a mailbox every so often. Of course you're going to be going back to turn in quests and such, so this really doesn't save you a whole mess of time.
In the end, I don't see this having a significant 'game-breaking' impact on the players of WoW. It may give a small edge, but it doesn't provide you with any functionality that you wouldn't normally have if you were logged into the game. This just lets you check on stuff while commuting (or sitting at your desk), it doesn't let you pay to play remotely.
I think this is a good thing, but it's a little closer to the bad Micro-Transactions than say the pets or mount are.