That won't happen until 1BTC equals 1kg or at least one pound of Gold. One Oz is not that much money after all (2500$ is a month's wage in the Western Hemisphere).
1 bitcoin = 1 kg worth of gold will never to be real, It means the bitcoin must be worthed over ten thousand dollars.
OP, Bitcoin is not flipping the gold. My thought if the bitcoin is different with the gold itself. The value of the gold depends on the how many weight of the gold itself. And bitcoin is not.
well it's not that unfeasible to have bitcoin worth $10k or more, will happen eventually in the near future
bitcoin is more rare than gold, and therefore the chance to have it with a better value is high
also gold will never grow more than that, gold is there in its stagnantion since ages...