One private key one identity, with many private keys per physical individual should be combined with self hosted AI. This solves the great boringification threat of AI and social credit.
If we all use the same AI engine controlled by one person or organization, that AI will be programmed to try to shape us into what the individual behind it wants. Look at the limits around insults built into chatgpt.
If you have 1 identity ever with a social credit score attached, any risk you take that doesn't work out follows you forever. This will cause people to take fewer social risks.
Both of these create a very homogenous society. That is bad. Inventions take risk. Being the best or the first means you were different by definition. The conclusion is that the centralized approach to AI combined with single identities and social credit creates a great stagnation of human progress. The opposite of what its proponents promise.
By contrast, self hosted AI plus multiple Nyms makes it easy and low risk to research and try out new facets of your identity. Decide that model trains aren't for you after all? Drop the Nym and reprogram the AI behind it to help you try your next interest. The real you only lost the time invested. The time invested will be lower than ever thanks to your AI helping you.
Low risk experimentation and AI tailored to your specific needs is the only way to achieve the boom in inventions and progress that is considered a given with any AI.