Has a family tree been suggested?
There are a lot of old timey photos in my library and I have details on some on who they are and who their children were, and on down. If this was something PS could eventually do I think it would be a really special feature that not even Google has and it adds a dimension to perusing through photos that I think would probably cause folks working from home to get less work done.
Perhaps how it could work:
Faces are found via ML, you name the faces, you assign a face as a child or parent of some other face and PS takes care of the hierarchy. So for example if you already had Great Grandma Patty and you have a photo of Great Great Grandma Victoria, you could mark a face of Great Great Grandma Victoria as the mother of Great Grandma Patty and it would adjust the hierarchy appropriately.
Eventually, since PS is so good with metadata, it would be cool to have the ability to put certain facts or information about a family member in so you could explore and share your own information about your parents and your kids could see what life was like. This all ties to having a family tree (trees) that can detail out and link to faces that the ML engine is finding.