In the past, China and Russia have suggested replacing the dollar with the IMF's Special Drawing Rights (SDRs), as have the likes of France and Germany.
Created in 1969, these assets were initially tied to gold but are now based on a basket of five currencies: the euro, renminbi, yen, and pound sterling, in addition to the dollar. However, the supporting countries haven't been able to make SDRs happen.
A widely used gold-backed BRICS currency would be a dream come true for bloc members such as Russia and Iran, as they're currently sanctioned to the hilt.
China could invade Taiwan without worrying about the US completely cutting it off from global trade and the currency would also be a boon for two newer members, Ethiopia and Egypt, who are both currently plagued by dollar shortages. Brazil is also keen.