Keep in mind that when the current fiat currency collapse, there will already be in place another fiat currency to replace the ones that we have and are using thus far...Do I smell SDR's? To answer your question though, I would say the crypto that has established a base of support and trust that is backed by gold or silver would most likely be the crypto that would be used, and since we have 1000's of years to base off pricing using gold and silver, this mostly would be what would happen.