If you haven’t read it, Sarah Gooding did an awesome job summarizing what’s going on with Phase 3 of the Gutenberg editor. That’s the collaboration phase with real-time co-editing of posts as you get with Google Docs.
Here’s a quote from Matt Mullenweg about Phase 3:
Phase 3 is Workflow. This is basically where we’re going to take real-time co-editing into WordPress, much like Google docs or something else. When you log in to edit a page or your sites or a template or something, if someone else is in there at the same time, you’ll be able to see them moving around. Of course, we want to make sure we have version control built in like we do for posts and pages, into as many parts of WP as possible, so if someone makes a mistake or an edit to the site, you will be able to roll it back easily, which I think is really key for giving people confidence.