I don't know why people keep acting as if western sanctions are supposed to mean anything to other countries. The only legal international sanctions would be issued by UN.

It's also worth noting that a reserve currency is not any sort of necessity for global trade. Countries can just do trade in their respective currencies and hold commodities such as gold in terms of assets. What makes yuan attractive for countries is the fact that China is the global manufacturing power house, and countries can always use yuan to pay for things they need to purchase from China. Given that China is already the biggest trading partner for most countries, holding yuan becomes a safe bet for them.

I do expect that we'll see dollar based economy shrink fairly rapidly, especially with Saudis and other oil produces now selling oil outside the dollar. The fact that you could only buy oil using dollars was one of the main reason why there was a constant demand for dollar.

The most likely scenario in the near future is that we'll see a bifurcated world economy between the BRICS and the west.