When I wrote about emergency funds, I was thinking along the lines of an unexpected repair or doctor's bill or a job loss. It is true that in the United States we have a stable currency. We, also, only use one type of currency.
I look at the issue of currency wars in a different context as emergency funds. In regards to currency problems, I would definitely agree with your belief in keeping several sources of currency at home. Perhaps gold coins too. As Russia and Switzerland have proven, currency can devalue and fluctuate within a very short period of time. You want to have assets on hand in those cases.