I think this is a great idea! Yea, sure, you'd have to think about security and, of course, how will SEO be affected, however, much the same way we can embed content from FB, YouTube, etc. into a WordPress.org Website, users should be able to do that as well.

I see if formatted much the same way Jetpack displays Related Posts on a self hosted site, except with an excerpt. So, a square or 4:3 ratio image (if available) with the title, excerpt, author, and domain in the embed.

I can see this replacing the Press This in the future much like the way Menus and Link Post Types replaced the Blogroll.