Nice workflow.  I was thinking lately that new users might not understand everything about key pairs at the start.  But could learn about it later.  So in that case, a key pair could be generated for them.  Later they transition to a self-sovereign key pair.  There would  need to be a way to keep track of this.  I am already starting to look at versioning of profiles in #nosdav so that you dont lose your contacts list.  If this were combined with a notarization event it would be possible not only to allow new users to take control of their own their identity, but also for existing users to rotate keys.  There would be a fee for this (size of fee depends on security), but it is a path that could on board a large new audience. 

 100% agree with key-holders being able to own their entire identity. That's follows, event history, mute lists, maybe even PMs, allow easy restoration. I'm still working on an issue for presenting a possible addition/change to nip-05 that allows extensions to present authoritative profile data. Currently under construction in NVault.  

 Profile migration across nsecs WILL be a needed feature on its own right, for MANY good reasons. Glad this is on your radar, and in the conversation.