welcome to the forum @Drdavidbell 
It will be simpler than you imagine because a system to provide this will soon be running as a sidechain of Cardano. Some pretty big projects, both crypto and conventional, are already queueing up and preparing to use this:
Like for the purpose you’ve imagined, it will allow users more control over how their ID credentials are presented, more or less according to this standard (this is a technical document but you can focus on this section Use Cases and Requirements:
Here is the description of a pretty big use case in active development:
Some conversation & developments about Atala have already been posted in this forum thread; the discussion of whether and when this platform will be “open source” will determine some of these use cases as well as the competition that might emerge:
If someone knows a blog or other resource where Atala developments can be followed directly then I hope they will post it here because I have also been looking for this myself.
I would think NFT production for certificates and sharing would develop as a matter of course from the fundamental requirement of unambiguously proving identity. My technical view is that a rigorous, unimpeachable ID system should first be there as the basic “layer” & then the NFTs, certificates, professional directories, etc. would be available as layers on top of that.