In a previous knowledge system, we used "tokens" to create consistent verbiage across multiple articles, this allowed us to update content in one spot and have the new information automatically pulled into all content. (e.g. a changed phone number could be updated in one place, instead of in each article it appears).
We also used this for company glossary terms. For instance, for HIPPA we provided a brief description of the term. Then the token HIPPA was pulled into several articles where HIPPA was mentioned. When hovering over the term, the definition would appear. However, the main request is for the functionality to pull these created tokens when creating new content.
This capability is on our road map, and would address your scenario from what I can see. The concept is similar to your description, in that we would allow the creation of "reusable snippets" of text, single sentence, paragraph, or entire section that could be maintained external to other content, but referenced in any article. Updates to the master "snippet" would then automatically be updated in referencing articles. I'd like to get this functionality in the 2019 time frame (target only).