Say there is only 13 tonnes left for the central banks to supply to the market, I reckon that's about $433 billion worth at $930 an ounce, i.e. not much if the Arabs and the Chinese got spooked re their US$ holdings which are already a multiple of this figure.
The Gold Cartel can only hold things in check while the aforementioned retain confidence in US Government paper. Personally, I think they have already lost confidence in it (they aren't fools) and all that's holding the thing together is US military supremancy. This puts the Arabs, in particular, in a difficult position, having a lot of US troops on their patch and enemies all around, and the Chinese worry about the carrier battle group patrolling the oceans and cutting off their supply routes...
When the big money moves, there is nothing the bullion banks can do to stop the explosion that will take place. Just got be postioned right and patient... very patient...