What I would like is a good way to create structured data admin systems that can include HTML content, and then have my static generator access that to build the pages via a JSON feed or whatever. For example, having records for individual products including a body description which can be in HTML format. This means that other people can update the products, but we still have a static website. I thought Airtable would be suitable but surprisingly it doesn't support HTML fields very well.
Not sure if this helps but Decap-CMS lets you define your own records with fields, like a shopping product record with a price field and Markdown/HTML description, where the content is saved to Git in simple JSON/YAML data files. You can then edit the records via the browser web interface, which commits changes to Git and your static site generator would build the site from the data files.