Bitcoin can't directly replace oil and gold but it may replace the demand and effectiveness of them. Oil and gold are most useful thing in the world but bitcoin is a digital currency that can be use instead of fiat. Bitcoin will accepted widely and it will handle the economy soon.
How is that? Bitcoin has turned out to be a very useful entity that is making all the investors Rich if I may say so but replacing both Gold and Oil doesn't seem likely as those two items have their different uses as well. We can argue that BTC will over shine Gold and oil in price, if it hasn't already but it terms of what they all provide, I will say they all have their Unique and one cannot replace the other in that regard.