End-to-end encryption was rolled out by default to WhatsApp not too long ago, and reports emerged of Facebook intending to do something quite similar to Messenger. Adding more fuel to the rumor is today's leak of an alleged Facebook for iOS app changelog that leaves little to speculation.
The alleged changelog, leaked by @iOSAppChanges on Twitter, covers a number of different changes with two specific references to encrypted or protected communication including a mention of "end-to-end encryption" as well as a reference to "secret chats."
Some of the other things mentioned in the changelog include changes to privacy settings, the ability to add reactions to Facebook comments, and "more Touch ID support."
It's unclear when any of this is coming, or if it is coming at all, but these changes will be welcomed by the security and privacy focused users of those services. Facebook has had an interesting relationship with privacy in the past, which includes a recent policy update that emphasized Facebook is even tracking those who do not have a Facebook account.