I have actually discussed the concept in the past [0], and I exchanged some emails with the guy in that thread to talk more about technical details. We all seem to agree that design and political will are the problems, not technology.
What I was basically saying in the comments, in general terms, is that you might have one primary identifier, and then somehow you can get more identifiers that are tied to your main one, but that might have different expiration periods, might grant access to different levels of information about you, and might be limited to a certain number for each service you use. Of course, there are quite a few ways to implement such a system. And that's precisely why I'm more focused on the design, usability and characteristics than the underlying technical implementation; I think the best we can do if we ever want to see this happen is to spread the idea in terms that anyone can understand [1]. I mean, I'm interested in the technical details too, so I'm just complementing and contextualizing a bit here.
[0] https://news.ycombinator.com/item?id=22180120
[1] ...or discuss more the idea among those that are interested and setup a demo website to make it easier to spread the word, even if there's no actual implementation behind it and it's just a mock-up. I'm quite busy at the moment, but I'll definitely do something along those lines when I have some time.
Actually, I would prefer: "Yey, this one-use temporary ID is tied to an identity which is known to behave on public websites." Or "... is tied to an identity which is known to be knowledgeable on topic X". Or whatever information is needed at the time.
Next time a new ID will be generated and the identity provider will vouch for it. No passport or phone number should be required.
Edit: fixed spelling.
Yes but no. Anonymized identifiers can be deanonymized. They should utilize zero-knowledge proofs in such a way that they can prove "yes, I have an identity verified by entity X (and Y and Z) (based on passport/phone number/...)", without disclosing any of those details.
It could, optionally, yield an identifier unique to each requester and unlinkable to others unless an explicit proof of the link is provided. Though if this is included, there has to be some mechanism to avoid huge ad networks sharing the same "requester entity".
This is a solved problem. All that's left is politics, implementation and alignment.