The only person I have ever met who invested in physical gold (coins) on an ongoing basis was a survivalist who basically kept them under his bed with the aim of bartering them when the system broke down.
It is possible to invest in gold funds etc., but many people like to physically possess it.
Could Bitcoin overtake gold on this basis i.e. an asset you alone control without having to keep it under your bed?
The answer is No.
The amount of places you can spend bitcoin shrinks by the week, because of scaling issues, so it's worse than gold.
However, there is a chance that an alt might take the place of bitcoin and be the substitute for gold.
For example, this week Stripe (payment processors) announced that they were dropping bitcoin because it was unusable. But at the same time they announced they were thinking of enabling LTC, BCH, ETH and stellar lumens in bitcoin's place. The more people that do this the more likely it will be that bitcoin gets taken over by an alt.