Very interesting post.
I really like your comparison of mistaking a map for reality. The complexities of proving identity have been around virtually as long as humans have walked the earth.
It's great that we're thinking and talking about these things. The concern I would have in a system like this is how does one prevent groups of malicious individuals from claiming the identity of another person? And also, how does one who's put the claim to their account in the hands of the family and friends who know them make sure that their accounts are also secure?
Unless I'm misunderstanding, an account would only be as secure as the accounts of their witnesses in a situation like this.