This is one of the reasons I expect both a very strong bull market in Bitcoin combined with a brutal bear market in gold and other precious metals. So we could see BTC / USD in the 100,000 to 1 million range or higher and 1 oz of gold dropping to 500 USD or even below 100 USD. In effect a major transfer of wealth from gold to Bitcoin, kind of like the move from horse powered transportation to motor transportation 110 years ago.
I don't believe at all that bitcoin's rise means gold's demise. When bitcoin rises and holders diversify, a disproportionate amount is going to physical gold. I think this offsets the (also large) percentage of gold hoarders dishoarding gold to buy BTC.
Fiat is the thing I don't see anyone is interested in this scenario. It is also an instrument of slavery, because for every dollar you own, someone else is in debt the equal amount. It is shameful to have balances in most national fiats for this reason (ruble, yuan perhaps exception).
This is my strategy. Once the market value of a bitcoin equals the market value of an ounce of gold, a yet to be determined amount of my bitcoins will be sold/exchanged for gold. A small percentage mind you, as I'm a believer in the long-term progressive success of bitcoin. If something catastrophic happens (fatal flaw discovered in the protocol, whatever...), I will go down with the ship, bag in hand.