first bitcoin has to gain a much more stable price.
second it has to be adopted by a very large percentage of the world and be known by everyone.
finally gold has to become obsolete so that people want to look for an alternative!
(not necessarily in this order)
then bitcoin can become kind of a reference for measuring value.
Once Bitcoin marketcap reaches 1 trillion level it will have stable price. Just like gold it has to little market cap now and can easily be manipulated but its growing fast.
See how Gold market was back in the day, very volatile like BTC. People think gold has always been stable whic is not true.