I don't think America will collapse either. I do think they may have had their day in the sun and could be experiencing the early years of a long and uncomfortable decline when measured against other countries.
The Japanese experience has been informative, in the absence of catastrophies like world wars, their past couple of decades has been marked by economic malaise while neighboring countries prospered. I foresee a long and slow shifting of economic power away from the USA, particularly if the current "trickle up" (sic) economic policies continue to enrich the 0.01% as the middle class declines.
I'm not sure if Taipan has visions of trading his gold (if he has any) for wheelbarrows full of devalued dollars or trading it for ammunition and jerky, but if it's either I'm still laughing at him.
Let's follow the logic in either scenario:
(Scenario 1) The world collapses into a post apocalyptic state where Mad Max and a bunch of psychotic biker gangs control the streets and all essential supplies. Can you imagine a portly, middle-aged Taipan strolling up to the gang's fortified warehouse with a few bars of gold to trade for food and ammo? He'd be a lot safer starving to death in his spider hole.
(Scenario 2) Currencies collapse as governments create hyperinflation. Taipan's gold is now worth many multiples of today's price in nominal terms only. The amount of gold needed to buy a cup of coffee will likely be similar to the amount it takes today. "Ah yes" say the gold bugs, "it's worked as a store of value", but has it?
Keep in mind that he said he didn't take physical possession of it, if he actually has any gold it's probably stored at the Perth Mint, a mere two day drive from his home. This is the guy who claims to have bought gold because he doesn't trust the pieces of paper the government issues as currency. If he's not physically holding the gold, what is he holding? He's holding the equivalent of a promissory note assigning ownership to some gold which may or may not exist. And who issued the promissory note? The same government who issued the other pieces of paper he refuses to trust. Duuuuuuuh!
I'm old enough to remember when the US Government issued similar promissory notes which were exchangeable for a fixed amount of gold, they were called dollar bills! In God We Trust, government promises - not so much.

In fond memory of Taipan, a model of modesty, decency, dignity and tolerance. Long may we all prosper from the tremendous legacy of worldly wisdom and specialized real estate knowledge which he left in the "Arguments" thread.