I Have a rather simple plugin https://github.com/CODESIGN2/WordPress-Content-Sections. I generally use on all client sites and even themes and child themes.

• It means people can update their site and easily manage content without
  • becoming programmers
  • losing that content during a theme change

I Even create plugins for that plugin.

One thing I'm super interested in (tried with Visual Shortcode API but it was buggy) is being able to support complex content embedding (ideally both read-only reference (oEmbed?) and read-write template).

Read-write templates are basically things like two and three column blocks, and maybe suits widgets more.

Read only reference pulls in a piece of content so that it's easier to

• edit non-widget rich content
  • without a pile of plugins
  • using WP editor
• centrally manage, share and create content avoiding copy-pasta
• augment third-party offerings

I'd love to see more ways to manage complex content like CPT's that are not meant to stand-alone, but rather be composed (in a similar vein to your ordering of elements.