When trading is here (auction house), gold is going to boom in value. Players will be able to buy manapot items as well as much needed crafting materials. While the AH will have a fee, I don't think it will be enough to handle a long term boost in gold. 
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Here is my suggestion:
Add a "Treasure Hunter" or "Gambler/Gambling" tradeskill!
Rank 1 requires 1 gold per try.... You receive random rewards or can fail.
Rank 2 requires 5 gold per try.... You receive random rewards or can fail.
and so on....
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The rewards can be treasure boxes, random crafting materials, very rare chances at valuable items..

EDIT: In fact, it could possibly just not be a tradeskill and just be an activity. You spend gold in certain values to go on an expedition or spin of a wheel... Whatever fits the vibe of the game. I think it would be cool to have a gold sink feature that was very RNG like that. Like a mini-game.

I disagree. Combat takes a ton of food and the success rate of cooking and fishing are so stupidly low that food is going to be very expensive. The trading of food is not a "gold sink" per say, but it will redistribute wealth throughout the economy.

I have a Blackjack mini-game in my game that's very similar to this idea, and it's addicting as hell. I'd love to see it on here as well. It would be a nice little thing to break away from the monotony of the constant clicking of buttons.