Sorry, but it's nonsense and it's strange to see it coming from Sr. Member.
I'm wondering what makes you to think that fiat may become obsolette and that human survival will depend on cryptocurrency. It doesn't makes sense. Having cryptocurrency only you have to rely on internet and electrocity. You lose access to one of these things and basically you're done.
People apparently forget that if something very bad happens, whether it is a global war or a major natural disaster, we can expect that there will be serious disruptions in communication or, better said, an interruption of the internet. If that happens, the things that will be most valuable will be food, drinking water, and medicine, and of course, means of self-defense.
Of course, we should not be pessimistic, just realistic and prepare in time for every possible scenario.
You don't even need apocalyptic scenario. Outage of some IT systems or big scale hacker attack would be enough to make huge problems. Remember Crowstrike issuess last year. I sometimes think how much we rely on various IT stuff and how little would be needed to cause global chaos.