I am working with @stevejpurves and @lheagy on Curvenote, which is a scientific writing platform that integrates to Jupyter. Our goal is to make it really easy to share, and remix interactive content from Jupyter into reports/papers, as well as make that content a bit more accessible to contribution from non-Jupyter/git/code/md people.
Right now we have a Jupyter extension that adds some version control and commenting to Jupyter, and then allows you to remix outputs/figures/etc. into articles that you write in Curvenote. When you comment on/update something in one place that comment shows up wherever the cell/output is used - including directly in Jupyter. That works for content as well, and the default we have chosen in MyST.
Bit of a screenshot here:
I have been following along on some of the RTC work and really excited about it. 
We recently open-sourced our scientific editor as well as some of our commenting components – which @choldgraf almost got us to call “floaters” – alas.
I am always inspired by the tutorials that I see in Jupyter, and want to help make that sort of content easier to write/edit and collaborate on. 
If you want to give Curvenote a try, you can signup or get in touch by email: rowan@curvenote.com
Looking forward to working more with this community! And would love to answer and questions about curvenote/our-plans/overlaps!