BRICS is more a trade agreement than a currency. Its development bank, which is designed to compete with the IMF, called the New Development Bank, was originally funded in U.S. Dollars ($100 Billion):
The Chinese would love to replace those dollars with Yuan, but the Yuan faces too many obstacles, for now, to establish itself as a worldwide currency. So far, it's a pipe dream. The capitalization for BRICS remains mostly in dollars.
BRICS has pretty successfully supplanted SWIFT as the electronic depositing agent among member countries that are not using SWIFT (currently, that's just Russia, and that's because they got cut off for being dickheads). That's one reason why the Russian people were able to shrug off that part of the sanctions.But that's like replacing SMS messaging with something else. Its only impact so far is in helping the Russians manage western sanctions.
I agree with your overall tone: America is a financial and geopolitical bully, but I don't think BRICS is much of a threat to the world order. If it becomes so, the U.S., Europe, Japan, and Taiwan (assuming we avoid WW3) will find a way to crush it.
The world doesn't live on the gold standard. It lives on the dollar standard. And dollars are all over the place, from remittances from the Chinese diaspora to drug cartels in every country, including Russia and China.
