If you are expecting a currency crisis, the best asset to buy may be gold. And people having been buying it a lot lately.
There is no perfect answer. Different people worry about different secondary risks, and do different things in response.
IF we look at history and dozens of cases of runaway inflation or currency crises (germany, argentina, russia default, venezuela etc) where currencies devalued fast in a short period of time - having physical gold (even 5-10% of the total portfolio) would have alleviated the pain.
people lost life savings... and will lose again, as history often rhymes again and again.