Just saw that. Thanks.
No clue how you’re going to do this and what the end result would look like and for sure don’t want to tread on core features. I hope you do consider an approach which may allow a developer to override the built in onebox. 
I actually do want to go further and bring in some tagging / entity and term extraction using some services like alchemyapi / semantria / diffbot into the links posted on this forum that I’m looking at developing, so figured this sort of plugin would be a good start for me to learn ruby / discourse at the same time.