Gold are the mean of exchange for thousand of years. It hard to be replaced because some people think that gold are much more secured than bitcoin which is too risky.
That's the reality, we are living in this world and we always think that those who exist longer are better without realizing that it's all about finding opportunity. Bitcoin is quite new and there's still more room to grow for success on bitcoin, therefore we should be wise enough to ride with the success which it's still growing, bitcoin will definitely change the financial system of the world, slowly but it's getting consistently use.