Strangely we had this request from a client also last week. Pretty much the same thing but an added level of complexity to have different 'Display Names' show against posts in different groups as well as to different users/roles.
So I guess what we need is some kind of event like Pre_Render_Displayname() that we can hook into and carry out logic on in a plugin that will effect all widgets that show a users display name.
We can then put in any logic we wish there. This would be good for connecting to 3rd party systems to get a users 'Real Name' or things here instead too if that was needed.
Also using this we could make users posts anonymous with logic too if required. This is something we have been asked to do before: make it anonymous on the front-end but track the real user in the back-end.
Michael Monteleone is this not possible with event plugins in 7.6 or the up-coming 8.0 at all?