I’ve been thinking about the “unlinked mentions” bit for a while, and conceptually I really, really like the idea - I labelled it in my head as “outgoing unlinked mentions” . It’s the list of all of the notes that might possibly be related to the note you’re looking at right now. Having that will let you identify linkages between notes that otherwise you might miss (especially in large vaults), and that would be awesome! 
So I started looking at it seriously to build out a plugin, and then got stuck on these points:
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if all your other notes are one word, then every word in the current note could be another note (especially the nouns). That could create a huge number of “outgoing unlinked mentions”, which might drown out the useful connections
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computationally, you would do this by making a list of all the other notes in the vault (including any aliases for notes) and then searching your current note for any of those names. Not insurmountable, but also not necessarily practical in a large vault either.
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Additionally, doing that kind of search this means only an exact match would show up in your “outgoing unlinked mentions”. That could mean you’d miss things (and would definitely not work at all if you’re using ZK prefixes).
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Because of the previous points, you’d also want to search for any occurrence of a word in the name of other notes in your note. For example, if I have a note called “Accessibility is important to usability” in my vault, and in the current note I’ve written the phase “A key point in uptake is usability…”, then there’s a good chance I do want to make an explicit link on the word “usability” there. But if I’ve written “It’s important to note …” then I don’t care, and I don’t want to be bothered with an “outgoing unlinked mention”. Problem is, how does Obsidian know the difference?
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Following from 4, imagine I have a note that has three phrases in different places:
- “A key point in uptake is usability …”
- “It’s important to note …”
- “Accessibility is a component of …”
Then I have three possible outgoing links (two of which might actually be real and useful to make). But if there’s also other notes in the vault with names of “Usability”, “Accessibility”, and “Good usability improves uptake” then I’ve got 5 possible outgoing unlinked mentions. How do I display that in a list though? They’re highly specific to the context and placement of the text in the note, especially if you image there are one or more other notes in the vault that have the words “key point”, “uptake” and “component” in their names as well…
Thoughts and feedback on this, am I missing something that makes it simpler than I think it is? (and sorry for the wall of text, but I couldn’t explain it in fewer words 
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Related (both my posts):