The project I work on, Netlify CMS (https://www.netlifycms.org/), is almost precisely what you described in your last paragraph.I say "only" because it only officially supports GitHub as a backend at the moment, from which you can deploy to a host. (I'm also currently working on supporting more backends, so that will change soon.) The CMS is an open-source (MIT license) CMS built as a static web page which connects to an API for an arbitrary backend from your browser and edits the content stored there - from there, you can build the content with whatever static site generator you want. This lets you build sites that non-technical users can keep up-to-date without tying yourself to a specific tech stack for the actual website.
Please put that description somewhere on the site. I tried to try out Netlify CMS there times because I love Netlify the service but couldn't figure out what it is any of those times.
That said, it didn't help that you don't support Gitlab, which is where all my sites are, and which is the more important reason why I couldn't get it to work.
Yup, improving backend support (and refactoring the backend API to make developing custom backend support easier) is currently my top priority. Initial GitLab support (without the editorial workflow) is very close to being complete - I hope to be releasing an initial PR this coming week if all goes as planned. My latest update in that thread is here: https://github.com/netlify/netlify-cms/pull/517#issuecomment...
I'm a huge fan of Netlify, everything you guys do is great.
We (Graphia) took a similar approach for our document management system. Essentially it looks and acts like a regular CMS but it sits on top of a git repo instead of a database; and publishes via Hugo.
It's not intended to be a fully-fledged CMS but the API would support it without much work; the UI is definitely the time consuming portion.
http://www.graphia.co.uk for anyone who is interested, not quite ready for prime time just yet. Soon.
That sounds really similar to Netlify CMS, especially the use of Git for content storage+version history and the focus on a decoupled UI for editing content. It's really cool to hear from somebody exploring the same space! Git as a backend for content is a really interesting concept that's worked very well for us so far, and I'd be interested to hear how you're implementing that and what issues you've run into. The internationalization approach you describe on the features page is pretty intriguing as well - that's a feature that we should improve our support for in Netlify CMS.
Feel free to ping me using the contact info in my profile or at @benaiah in our Gitter room (https://gitter.im/netlify/NetlifyCMS) if you're interested in discussing this elsewhere.
(disclaimer: Netlify employee)