Central bank digital currency: the end of monetary policy as we know it?

This is interesting, but I don't understand why the existence of CB coin would necessarily lead to traditional bank accounts losing their status as means of exchange.

Money is whatever other people will accept as money.

CBcoin accounts could be more stable form of money (though as many emerging markets show, it's not like central banks are always risk-free), but that doesn't mean it would crowd out all other forms. On the contrary, just seems like a return to fractional-reserve gold standard, where instead of gold, people use CBcoins...