Any modern society is relying on digital supports for most of its administration. Estonia is just proposing more "frontends" to its citizens. Not all of them decide to use it btw (article mentions 46.9% of people use online voting)
So if we're talking about "black swan disaster scenarios" or "catastrophic computer virus", I don't see any difference between Estonia and other countries.
So if we're talking about "black swan disaster scenarios" or "catastrophic computer virus", I don't see any difference between Estonia and other countries.