The main trading partner of every BRICS country is China (save China themselves). I think it won't happen, this UNIT. But I also think them choosing BTC is a foolish hope. BTC couldn't handle it, not even close, despite some fundamentals you and I both like (that China doesn't care about or actively dislikes). Trades will be mostly in yuan with some amount of hedging. 

 That's kind of what this is. Essentially Yuan with a 40% gold hedge. 

I have a bad feeling that Bitcoin is going to crash upwards alongside the demise of the USD, the global economy will rebalance around Yuan + gold and not a Bitcoin because it's rapidly becoming nothing more than a financial instrument within the USD economy.  

 OK I'm reading a bit more, I guess it's more like a modern replacement for SWIFT, the tokens not being an independent currency. Is that about right?

Crashing upwards, perhaps, but I think bitcoin will hold it's own. It has worldwide niche appeal as Internet money for the people that all attempted replacements have failed to replace. 

 government money is gonna be irrelevant when grid down and satellites falling out of the sky, but bitcoin will keep on ticking

bitcoin will only fail when the internet is completely ded, which is almost impossible