The BRICS will move to a single currency union with a gold-linked currency in the near future. But it probably will take at least 5 years to actually roll out such new currency for trade settlement purposes and even longer until it can be used as a reserve currency.
At the moment global reserves are held in following currencies:
USD: 60%
EUR: 26%
JPY, CHF, GBP, CAD, AUD and CHY: 14%
Sven Franssen