I think you're conflating the idea that a reserve currency needs to be the same currency that a person interacts with on a daily basis.
Commercial trade and government debt operate a such large quantities, that they are essentially a market unto themselves.
This is essentially how gold worked wrt the gold standard, except that with gold, a large find in one country increases the wealth of that country, or makes it subject to war, as other countries want to capture that value for themselves.
The reserve currency needs to be so liquid that the average person doesn't feel nations buying/selling massive amounts of currency for trade.
To believe Bitcoin fits this is to be completely ignorant of reality.
It would be questionable if the Euro is even liquid enough for this because of the bond market.
If you look at the Real, Ruble, Rupee and Yuan vs USD, the BRICS would like something else because USD is too strong.
To look at those currencies and conclude it is over for USD is just absurd.