This is rather utopic vision. None of the gold owners would sell significant part of their gold for btc - gold is used to store value for ages, bitcoin is a currency.
The thing about "store of value" principles is that the ascribed value of things changes. It generally has a floor of the marginal cost of production / extraction / acquisition, though sometimes it can fall below even that (viz: inflated currency literally not worth the paper it's printed on).
If someone's willing to pay more for bitcoin than gold, or you're betting that that the value of bitcoin will increase, trading gold for BTC makes sense.
In terms of tangible value -- Gold is more likely a persistent store of value than BTC, but where you need to move wealth quickly and easily (say, you're fleeing an unstable situation), a BTC wallet somewhere else might be a lot easier than smuggling out gold ingots. Even a (moderately) modest amount of wealth, say, $50m, would be somewhat over a ton of gold. Hard to run with that in your pockets.
If you want to limit yourself to a maximum of 45# of weight, you could carry slighltly under $850,000 at current market prices. Not insignificant, but depending on the loot you're trying to, well, loot, possibly less than you might hope.
http://www.dailyreckoning.com.au/silver-a-brief-history-of-d...