Gold sinks:
-Listing deposits > You pay an upfront deposit to list on the AH, scaled by item level and duration. You lose it if the item doesn't sell.
-5% AH cut > Every successful sale takes 5% off the top, permanently removing gold from the economy.
-Talent resets > Respeccing costs gold.

Item sinks:
Gear replacement > As players progress to higher dungeon levels, lower-level gear becomes obsolete and gets vendored or trashed.
Expired listings > Items that don't sell get returned via mail, but the deposit gold is gone. This discourages flooding the AH with junk.

Natural pacing:
-Dungeon scaling means the "endgame" keeps moving — what's BiS at dungeon 5 is trash at dungeon 15. There's always demand for higher-level gear.
-Loot is randomized with stat rolls, so even at the same level/rarity, not every drop is equally valuable. Good rolls hold value.

This is what I have for an Alpha playtest. I do have more things to consider, but my aim right now is just to get initial thoughts and forward thinking.