Most users don't care about reputation. Like most large tech companies, Facebook will be hurt when they miss a disruptive innovation or major social change.
The network effects issue is real, some kind of open graph could potentially be the answer, as upstart social networks start with the disadvantage of having to connect everyone somehow.
That said, I worry about the Myanmar thread: there, The Internet is synonymous with Facebook, and people trust it as an authority. The masses who are unequipped to think critically aren't going to be persuaded to choose something else as long as the platform keeps serving up paid "news" ads and click bait that reinforces their beliefs.
The powerful ability for a platform to target specific humans or allow any one to represent a trustworthy new organisation is problematic. These are interesting places to start too.
People risk their lives daily to read Facebook while doing things like walking across the street and driving. As long as people get their notification fix, they probably wont care that much.
A social network/messaging app isn’t that hard to build and Facebook has been building a lot of extra shit on top of it that people don’t really need.