Speculative musings, from an inadequate historical background.
We tend to take it for granted that the world looks like this, from a monetary perspective:
The world is divided into currency areas. Each currency area has one alpha bank (the king). All the other banks are beta banks (subjects, who follow the king). The beta banks promise to redeem their money for alpha bank money at a fixed exchange rate. The alpha bank makes no such promise the other way. Asymmetric redeemability. The alpha bank is the leader, who decides on monetary policy for the whole currency area. The beta banks just follow along, because they fix their exchange rates to the alpha bank. The world is divided into monetary monarchies.
There may be sub-monarchs, who play alpha to the beta banks within their own sub-area, but who in turn play beta to some greater alpha bank. Like when the Canadian commercial banks fix their exchange rates to the Bank of Canada dollar, but the Bank of Canada in turn fixed its exchange rate to the US dollar. The Canadian commercial banks follow the Bank of Canada, but the Bank of Canada used to follow the US Fed. The Bank of Canada used to be a sub-monarch, before it floated the exchange rate and declared monetary independence, and then became a full monarch.
Does the world have to look like that? Is monetary monarchy inevitable? Is oligarchy an unstable system? Can two or more banks play both alpha and beta to each other, where each promises to redeem its money for the other's money at a fixed exchange rate, and so share monetary sovereignty? Or will monetary monarchy inevitably reappear, where the strongest bank becomes the new alpha bank?
In the couple of years immediately preceding the Euro, and the creation of the ECB, were the central banks of France and Germany true oligarchs, who shared the pooled monetary sovereignty over France and Germany by fixing their exchange rates symmetrically to each other? Could this have continued? Or would one of the pair have become the alpha, and the other the beta, if the ECB had not been created?
Suppose the Bank of Canada disappears. Because people stop using Bank of Canada currency, so nobody ever asks to redeem their Bank of Montreal deposit money for Bank of Canada paper money. And because the Canadian commercial banks stop settling their own accounts on the books of the Bank of Canada, so none ever holds either positive or negative balances at the Bank of Canada. The King is dead. How long before one of the Canadian commercial banks becomes the new King? What determines which of the commercial banks becomes the new alpha central bank? Will it be the strongest bank with the tightest monetary policy? I think it will. The tightest bank will refuse to redeem other banks' money for its money, if that would force it to loosen. The other banks must either follow the tightest, who becomes alpha to their beta, or else declare independence and float their exchange rates. Most banks aren't strong enough to declare independence; nobody will use their money if they do.
Gold used to be the alpha money, and gold miners the nearest thing to an alpha bank. But gold became less used as money, and people used beta paper money that followed alpha gold. Then the beta banks stopped fixing their exchange rates to gold. They stopped following the king, so the old king was no longer king. The strongest of the beta banks, like the Bank of England, became the new kings, within their own currency areas.
Bitcoin is not a beta money, because it does not fix its exchange rate to anything. Is it an alpha money? Does it have beta followers, who fix their exchange rates to Bitcoin?
(Synmetallism, where a bank pegs its exchange rate to a basket of currencies, does violate this simple monarchist perspective. The beta bank follows an average of two or more alphas. And inflation targeting is like synmettalism. The King agrees to be bound by his own laws. (Bimetallism is where you can redeem your money for fixed amounts of gold or silver. Synmettalism is where you can redeem your money for fixed amounts of gold plus silver.))