The jury is out on the yuan, but the ruble has a long history of instability. Why should this time be different? Czarist bonds, anyone?
That said, our government has taken advantage of the dollar's reserve role time and time again. In fact, our government seems to like a weak dollar, because it makes the value of US wages go down, and therefore makes US manufacturing more competitive.
Wouldn't a strong dollar, weak union policy be a better way to go about that than our current weak dollar, strong union stance? Our wages are relatively high compared to the rest of the world because we carry a lot of dead weight in the form of unionism and regulation. Our workers have enough capital to be very productive, but they can't overcome that deadweight without help. A deliberately weak dollar is not the right way to provide that.
All that is common sense, compatible with natural economic law, and not allowed, currently, in the US.
Nations can and do grow out of historic currency instability (we did), and China (very stable and very undervalued) and Russia (growing stability over the last decade and winning over the Soros-Clinton attacks) have been moving strongly in the right direction.