Factors of the Bitcoin’s value

If Bitcoin is used to mainly pay for goods and services, then the main factors determining Bitcoin price will be the stock prices at the fond markets, gold price and currency prices in different countries, as well as informational coverage of Bitcoin market development.

If Bitcoin will be mainly used to pay for goods and services this mean it will behave very close to usual currency.
The currency price generally depends from volume of the goods/services market divided by the volume of the currency in circulation. That why when economy grows and there are more goods and services produced and available you need to add more currency for circulation (money are «printed») to prevent deflation.

But bitcoin have fixed maximum of coins in circulation and if the number of goods on bitcoin market will grow this means that bitcoin price will grow. So, in the model, where Bitcoin is considered mostly as payment currency its price will mostly depends on the volume of the market where it is used.

So, the statement in the article is incorrect. There is possible situation when stocks markets and commodities prices will fall in common currencies, but will still grow in Bitcoin price (and Bitcoin price in other currencies will grow as well). It will happens because you can't add more bitcoins to circulation to compensate growing market when Bitcoin economy grows.