I would accept that "Gold is dead", IF every country sells all of their Gold and starts HODLING Bitcoin. China is currently buying Gold, Russia too, as an opt-out instrument/commodity for economic crashes.
Which is quite impossible, there is no way people can sell their gold for no reason, when the government has not placed a ban on the use of gold, gold has been a very wonderful asset of investment, and many people have been made through it, and it has also been legalized as mean of payment which government themselves are using, so they would never give it up for anything.
When bitcoin came in to the picture, it only came as means of alternative to some of this things and not to replace them because even satoshi knows that it would be impossible for it to replace fiat and gold, the only thing is that along the line, it may just bet more popular than other means to asset because it is digital and virtually everyone is really going digital now, and our next generation are the ones that will accept this solution more than us.