An exciting post! I was searching for "content blocks" yesterday and now this post covers everything around the idea.

I think WordPress did a good job on improving the editing content with the editor (from simple text to drag & drop images and preview galleries and embed media). But it's too far from the true content creation tool.

Talking about content creation, it's interesting that the page builder plugins are doing this better than WordPress editor (except they use shortcodes). They provide some kind of content blocks (with configuration) and some basic elements (like rows, columns). Besides, the frontend editing makes them a good tool for this purpose.

It's worth noting that there are a lot of intesting ideas in the discussion at make.wordpress.org!