Gold is perhaps 0.1% of the world's reserves in terms of a store of value. It used to be something like 50%.
Nothing is going to happen to Bitcoin, it's just that alternatives will become much bigger than it.
While it is obviously not 0.1%, it's also true that it is not as high as it used to be, gold did lose a lot of its power as a store of value because it is too slow. People are looking to make 10-20% a year, and they know they will only get rich if they can reach that 10%+ a year, and they know that gold will not bring that easily, so they are aware that they will get bad results. This must be the obvious reason why people started preferring bitcoin over gold.
We should probably look into how altcoins will do on the long term, and because of this I believe we are going to see them have a different result. Things aren't always that simple, we need to make sure addressing different economic problems time to time and because of that we are seeing how things aren't always that clear. Of course some altcoins (like usdt) are still strong, and would be preferred over gold but definitely not up to the level of bitcoin.