In a world where nations are losing trust in each other and everyone wants to dominate the world. They do not want to hold other countries' currencies and that is why the demand for gold has skyrocketed in recent years as central banks are trying to accumulate gold instead of currencies like the USD.
This is clearly a huge opportunity for Bitcoin and the Bitcoin era is coming. Due to its decentralized nature, it is arguably the perfect solution that the multipolar world needs. An asset/currency that is not controlled by anyone, easy to trade, store without permission or fear of confiscation or freezing. Most importantly, it solves the problem the world is facing, which is that the world does not need to trust any country and fear that one day they will become dictatorial and abuse power.
Maybe we should distinguish global reserve currencies from global reserve assets. The US dollar is the global reserve currency, mostly because it's being used as a medium of exchange in international trade. Gold is a global reserve asset, because the central banks are using it to backup the value of their fiat currencies. Bitcoin can be used as a supplement of gold, and more central banks could include BTC in their reserves, but I don't believe that BTC could ever replace the USD as the global currency, mostly because the BTC blockchain can't handle a gigantic amount of everyday transactions. Gold shares many of Bitcoin's qualities. It's a geopolitically neutral asset and it isn't tied to any particular country.