You know when you insert paste a link into chat there is a nice info tile, why isn't there something like that in the actual sites? I think it would be great for when you think there is a relevant answer and question, when you think the question is a duplicate.
Chat doesn't allow formatting when you use multi line. It would require a significant amount of effort to reproduce this in chat. However, there are a lot more options when making a real post. You can use editing all over and there are many more options for markdown.
In this post, you can make the same piece manually with little effort.
versus the chat one-box
So it wouldn't really make much of a difference. Also, most of the time, just the title will suffice: FAQ for Stack Exchange sites
Chances are, if you are going to need to show an entire one-box of another question in yours, it is potentially a duplicate. And if it is closely related, then showing just the first few lines probably wont capture the context properly.
Also, this would be terrible for comments as they extend far enough. If someone placed 4 links in a comment for related or possible duplicate questions it would be too much noise on the page.