I had some of my own musings over the concept of identity on steemit, which I summarize as having three components: A) Physical B) Digital C) Consensus. The way we have unofficially structured the introduceyourself posts provides some clues to the points you have raised and I have tried to address with the post:

https://steemit.com/makesteemitgreat-again/@plushzilla/the-steemian-identity-crisis-what-a-picture-of-you-holding-up-a-card-really-means

What are your thoughts?