I think it would be super fun if they added a mechanic that allowed a stealth/pickpocketing minigame.
Since they already have the legion class hall set up thats where the “thieves guild” would be stationed. This would allow rogues to walk around the current major city and pick pocket/steal items from Npcs and vendors. Each item would be worth a current amount of non-gold currency that you can then sell to a launderer. With that currency you can buy toys, transmogs, pets, spell appearances, just anything cosmetic unique to this minigame.
To make it actually fun you could even add guards and bounties/punishments for being caught. Nothing that would make your character unplayable but it could just be, you get arrested and ported back to a jail that you have to fight your way out of. You could also just force the player to lose whatever unlaundered items theyve stolen, stuff like that.
This is probably too deep for dev time to be worth it but you could also add a torgahst style skill tree to the minigame. “Laundered goods are worth X% more” “Guards will now take bribes to look the other way if caught”
I think something like this could have an insane amount of potential and would offer an alternative to just farming ILVL. IO, or world quests and it would add a lot of flavor to the major cities