It's difficult to keep gold that you don't have, disregarding that i'm saying the demand for gold will increase in TBC, due massive gap between regular flying and Epic flying (60% vs. 280%) and powerful craftable items.
Consumables won't be cheap either, less extreme than in Classic, but they will still be there, especially because Phase one won't offer an easy access to flasks, thus people will still need Black Lotus for Tanks, Healer and Caster Dps Flask.