By implementing the Ace Collaborative Extensions users could simultaneously edit the same documents in the admin and see what others are editing. This would allow two editors to edit the content of a page, the details of a web app item, or two developers to work on the same CSS file in the admin without over-writing each others edits when saving.
The idea is to allow each user to have a cursor of their own colour when in a document so that each user could type and add their edits to a document simultaneously.
This feature is primarily client focused, but could also be useful for partners who have multiple developers working at the same time.
The best existing example of this feature is Google Docs.
Here is a screenshot of what the feature looks like in GSuide/Google Docs with each user having their own cursor.
This wouldn’t benefit partners with multiple devs as we still can only have 1 partner portal login (and adding 3 team members to every single site manually is a waste of time), so we would all still appear in the same colour 
I think that having multiple partner portal logins is in the pipeline and something that we will eventually have.
For the time being, I can see adding multiple devs as regular admins if they wanted to work together, then removing them once the site has launched.
Honestly, our dev team is solving this problem with VScode liveshare, so this isn’t necessarily a dev feature that I’m looking for, but I thought it might be an easy implementation as it a plugin that’s already built for the ACE editor, and could solve some simultaneous editing issues for clients. I could also see some dev teams perhaps using this from time to time.