I think that would take a really long time before it happens. Most governments believe in gold and use the metal as their reserve currency if I'm right. The US, the Germans, the British, the Japanese governments and most others love to back their economies with gold. Few countries are serious about using Bitcoin as reserve, but this may change in the next ten years, especially with the increasing interest in Bitcoin ETFs. I would project that Bitcoin could be at par with gold in the 20 to 30 years due to increasing affinity to digital technology.