-——There are only two stable currencies that could replace the dollar——
Nope, there is another, better and universally accepted medium of exchange........ gold.
Currency as a medium of international trade is anomaly. Gold is the norm. World trade will revert to the norm for settlement between banks negotiating the international transactions .
True, and both Russia and China have been acquiring large stocks of gold, I suspect to declare a gold standard for their currencies.
The effectiveness of this will be if Russia and/or China are perceived trustworthy by the rest of the world.
The US (government) has been going the wrong direction (as opposed to Russia and China) in monetary and debt policy for two decades, and is becoming perceived as untrustworty.
Should Russia and China back their currency and be accepted as trustworthy, there will be foundational changes in world economic activity.