Folks don't CREATE a world reserve currency out of the blue ~ they just end up with it.
It's "the market at work".
Big China can engage in a great deal of world trade because they hold enough dollars to pay for just about anything they might buy. Without those dollars they'd pretty much be limited to whatever it was Hong Kong could generate for them.
Exactly and people need to realize that the Chicoms need the Americans to buy their junk, but we don't actually need to buy their junk.
Twenty years ago the Yen was "destined" to be the new reserve currency, then it became obvious that the Japanese economy was largely smoke and mirrors; ten years ago the Euro was "destined" to be the reserve, but that turned out to be a sham.
People can worry all they want about a new "global currency" taking over, but it would take decades for the world to be comfortable with it and (as demonstrated by the Euro), its appeal would collapse as soon as any sizable member nation showed strain.
America had had the world's largest economy for nearly a century AND America had just financed the bulk of WWII AND America had just financed the rebuilding of the world after WWII.
A new world currency only happens when there is a logical replacement.