I think they should remove the media content they add to external links and only show URLs. If people had to click a link to see the title, summary, images, or other clickbait meta content they'd be less likely to share links thoughtlessly. They might also see that the URL is untrusted and choose not to click through. Facebook could charge brands to show their content alongside click bait media. It would be a lot easier to verify the authenticity of ten thousand brands than every random link that's shared.

Wouldn't solve all the issues but it would be a start.