The bulk of the article contained arguments against the USD as a store of value, with little on oil and gold which were only criticised in hindsight; as an effect of what could possibly happen in the future. This suggests that they think fiat is the most flawed system as a store of value.
I was more interested in the piece about oil. I come from a nation who's primary source of revenue is crude oil. With the world moving fast towards more safe and renewable sources of power, it's a strong argument that oil would not be as valuable in the distant future, the more people realize this, the earlier a switch can happen, drawing the crash closer.
The supply spike argument for gold is a bit vague, it's possible as studies has shown, but efficient space exploration would still take some years.
Also, a crash in gold or oil doesn't translate to a switch to Bitcoin. While Bitcoin and gold are usually juxtaposed, investors are not limited to these options. If the USD fails, we would likely see the legal tender of another nation emerge as the widely used source of reserve.
To the prediction. Any price is possible for an asset such as Bitcoin with a limited supply. $500,000 is a realistic figure, the question is when that price would be reached?