A way for editor users to include unlimited (or limited but scalable) content within their blog feed without the collections needing a "field 1", "field 2", "field 3", "Field 4"... information architecture.

I am thinking this would require an array of elements that have been premade in the designer for editor user selection.

Maybe it's an array that is selectable in the rich text field type or it's a new field type.

The example of where this would be useful is in specific element interactions or wrapping elements in custom code (like social sharing) that only effect the specific piece of content.