Imho I believe that if the US$ collapses then most dollar nominated currencies like the NZ and AU dollar will suffer, with the C$ probably to a lesser extend.
The A$ price of Gold will go up as even the gold price will not underpin our currency enough as most big goldminers in Australia are now in foreign hands hence most of the profits are now being repatriated oversees.
On top of this our foreign account deficit will always be a big negative that would be more apparent by any hick up in the financial markets.