Note that I'm talking about our main chat server i.e chat.SE
The parent user in chat profile serves two important purposes today:
Base for being able to talk in chat
We know that when a user get 20 reputation on any SE site (excluding the case of SO and MSE), s/he can talk in any active chat-room on main chat server. Which I discussed as Chat related privileges are not site specific. Here the parent user provides a base to talk in any active chat room on the main server.
Name and Avatar
As user can talk in any room, name and avatar of a parent user is used to identify him/her.
Now upon the discussion Show the avatar of related site of a chat-room instead of parent site of a user, I've found that there will be no point to the parent user (above mentioned 2nd point) if we implement drawing name and avatar from related site.
As balpha ♦ already declared in the post What is the point of the "Parent User" in Chat? that parent user is, for the most part, a relic.
To be honest, much of the "parent user" idea is still a leftover of the original plan to let each StackExchange site have its own chat site.
I don't know if we're ever going to totally get rid of the idea of a user's "main site", since most people have such a site that they consider to be the most important (if not only) site they're active on, but over time, this idea should disappear into the background more and more.
So, I think we should have some idea to get rid of parent users by identifying the user by related site of chat-room instead of parent user.
But we've to compensate for above mentioned two points if we want to get rid of the parent user mechanism. I've some suggestions:
- When a privileged user enters a chat-room, use Name and Avatar from/of his/her profile of related site to that chat-room.
- If a user doesn't have an account on related site to the chat-room then apply one of the following:
- Use the parent site mechanism and user Name and Avatar from parent site.
- Use Name and Avatar of Network-Profile. (remove parent site mechanism)
- Force/prompt user to join the community. (so that s/he get Name and Avatar of related site to corresponding chat-room)
In my opinion, the 2nd option is the best. (As now you can also control what account to synchronize your network-profile with.)
Well, is there any thing we've missed? yes, the diamond! Moderators will not be identified as a moderator on the chat-rooms related to other sites.
But I think it may be OK for a moderator to be identified as a moderator only on chat rooms related to site on which s/he is a moderator as s/he is a site moderator not MSE moderator. So, We'll need to provide a diamond that works through out main chat server to moderators.
 I was free from estimating/guessing possible programming/coding complication!