The challenge is that, while the US dollar is beyond the control of other nations, its management, the Federal Reserve Bank, attempts to be transparent and can be easily followed by its counterparties.
OTOH, other than China, whose currency management is well defined, the other countries regularly wrestle with the extremes of inflation. While a currency bask is what it is, having a volatile bucket makes things hard to predict.
I suspect that while there will be nods to SA, B and I and a bit more presence by R, if the pot will be GDP based, China will be in control.
Jeff