Blizzard added to an earlier thread about gold farmer banning on the forums by outlining their plans how to get rid of gold farmers for good in patch 2.1.0. It turns out that this is easier than we thought. There are only three ways for a gold farmer to pass gold to his customers, and Blizzard is blocking all three, without causing too much hardship to regular players.
First is the mailbox, which after patch 2.1.0 will only transport written letters. The possibility to attach items or gold, or to COD, is going to be removed. Mail is currently the top distribution method for farmed gold, so good riddance.
Second is the auction house. Currently you can transfer gold via the auction house by the receiver selling some worthless item for 1,000 gold. To stop that, the ability to freely set the price of items in the AH will be removed. Today already the minimum bid price is set automatically. Starting from patch 2.1.0 the buyout price will also be set automatically, at twice the minimum bid price.
The third method to transfer gold is the trade window. Totally removing that wasn't possible, as it is needed for things like lockpicking and enchanting. So Blizzard cleverly transformed the trade window into a tradeskill window. Just giving somebody items or money isn't possible any more. But a crafter can select one of his recipes in the tradeskill window, and it will show the ingredients list to the customer, plus a fixed fee. If the customer fills in all the materials slots, the crafter can craft the item, and it will directly appear in the backpack of the customer. Even bind on pickup items can thus be crafted for somebody else! Very useful.
With no more way left to transfer gold to their clients, the gold farmers will quickly go out of business, Blizzard hopes. I'm a bit sceptical that this will only half work: Powerleveling is still possible, and if you give your account to some gold farmer, he could farm gold for you on your account. Less practical than the current method, but there is always one way left to do it.