Let's state instead a fictional scenario: you got an email from John Doe, is really from him? Well, if it's signed with a GPG key signed by a government authority probably yes (at least, if it's not him he have successfully steal card&credentials to sign his key or something even more complex). Did you know the small "key-icon" GMail offer in it's WebUI for "trusted messages" from some well-known vendors? Well, with this you can replicate the same with anybody in Germany, trusted not by a private company but by a government authority.

It's still marginal since most would not use such system, but potentially it's a pretty logic idea and a very good news.