If the real price falls, it can't go much below the production cost (currently averaging about $1,100/oz).
Not saying that I believe gold will drop below that, but I don't see how production cost forms any real barrier for gold price. Surely the newly mined gold is only a very small part of the overall supply in the gold market? It doesn't matter if the miners refuse to sell below their production cost, if everyone else is. Or perhaps you meant something else?