The AH and such will be a different place anyway.
Some people might pick a new weapon because they're running around with one that is ~15 Levels below their current level.
Next to that, crafting materials will be worth a ton because people have to level their profession to max and pretty much everyone wants crafted stuff even at 60.
In a world where AoE spells and AoE looting aren't a thing, farming even linen cloth as level 60 in RFC might take a bit.
Also, getting the "right" world random drop might make you a "rich" person, getting a Krol Blade and then selling it might allow you to buy another epic beneficial to your class.
Selling certain items required for quests will also be a thing (Deadly blunderbuss on Horde for example), all those gems required for crafting, etc.
There will be a lot of people seeking to control the market, since Gold is extremely valueable to anyone in Vanilla, but there are tons of markets to control.