"So while the dollar is falling, another currency is strengthening, right?"
Only for a very brief period till the falling weight of the dollar drags it down in a crash of its own.
A dollar collapse is so heavy no efforts to support it can succeed. Other currencies will shoot up against the dollar but because global economies are so interwoven, also apart from oil, the collapse becomes like a black hole sucking ever other currency into it and also virtually every other economy.
The survivors are those who grow their own food, weave their own cloth and can somehow need very little medical care. Barter becomes the final arbitor.
Unfortunately, as one of my friends remarked on this, if you hit people with a sledgehammer of truth and reality - as in this case - fear will make them reject you and the facts behind the premise.