1. Regardless of the crisis, some currency remains (or becomes) a reserve currency.
2. That country has for the past few hundred years always been an industrial power.
3. The currencies that have effectively died seem always to be connected to countries that are highly indebted or politically unstable.
4. Gold's price may look attractive now, but its price also has a habit of collapsing when people start to return to the market, making it more of a speculative gamble than a safe reserve (at least, talking about TRADING gold, not the physical stuff). If you live in a non-G7 country, maybe holding physical gold is a good idea if it seems like your economy might totally collapse, but in the G7, if your currency totally devalues, it means that the entire world economy has gone to hell and there are more important things to worry about than how much "savings" you have, like how much food and water you have.
Given 3, even if you COULD buy RMB (it is illegal to take RMB outside China, so how exactly would you spend the money, unless you are willing to move to China?) their government is a group dictatorship one "unexpected" event away from collapse, despite everyone's hopes for continued calm running. Britain is too small to resume reserve currency standing, and most of the other US creditors are of questionable long term stability.
Except for Japan. They have insane savings, have not gone to war since WW2, and have a government so focused on stability that Koizumi made huge waves with his "controversial" plan to privatize their postal banking system -- a plan that would not even take effect until several years after he left office. The Yen may not appreciate much, since no one likes to see it go much higher, but I would love to hear someone explain how it could possibly drop much either.