Well the former pretty much describes the current state of affairs. Anyone with a government ID card or national healthcare ID probably has a chip embedded with an escrowed signing key. There's really nothing unique about Estonia here -- they're using the same system everyone else is using. Even if your country, like the USA, doesn't have a national ID of some kind or doesn't have a chip embedded, your passport does. The international standard governing "smart passports" being issued by just about every country in existence for the past 5-10 years includes embedded digital signature capability.

Now I don't really know how to estimate the probability of sliding into the latter case. I don't see them as intrinsically connected however.