I can tell you how that will be: Like in Europe after WWII when people traded a Persian rug for a sack of potatoes, later for a pound of potatoes after the farmer already had a Persian rug in his pigsty and a Monet hanging in the horse stable besides having his dog eating out of sterling silver.
You gold coin has no more value than what somebody will want to give you for it. And if the guy at the hamburger joint waits long enough you will give him two Krugers for a hamburger.
The only thing that has value once the monetary system crashes is what you can produce not what you wasted your money on before the crash.
As for what value people are giving you for it? They're giving you way more than the spot price consistently every day! Visit the largest online marketplace in the world and take a look and stop lying to yourself to make your preferred bondholder status feel better. If you think a currency crisis and the upcoming runs on the banks that you will suffer from in Greece and all across Europe are going to change what is proven daily already right before your eyes, I don't know what you're smoking but you can keep it to yourself.