Group FaceTime calls possibly coming in iOS 11 →
Presumably this would include FaceTime Audio as well, which would finally bring it to feature parity with cellular calling.
If this rumor is true and a team within Apple has been giving FaceTime some attention, I can imagine them going further than just adding group calling. Maybe bringing Screen View over from the Classroom app that rolled out with iOS 9.3? That implementation worked over a local Wi-Fi Direct connection, but iOS 9 also included ReplayKit for local screen recording, and iOS 10 expanded on that with ReplayKit Live for streaming games to services like Mobcrush.
Perhaps most compellingly, a few months ago my Dad was escalated to a senior AppleCare support specialist while troubleshooting a family member's iPad Pro. Eventually the specialist asked if he could start a screen sharing session to walk my Dad through some steps, similar to Amazon's Mayday feature. When my Dad agreed, this message appeared:
Share your screen with AppleCare?
If you tap Accept, AppleCare will be able to see everything on your screen during this support session.
I wasn't there to see the session take place, but the status bar turned a different color (can't remember which) and the specialist was able to see everything my Dad tapped on until he terminated the session. This capability is barely discussed online, except for a brief mention of it on Apple's support site back in late 2013.
Something like this would make troubleshooting the devices of long-distance family members way easier than aiming a second iOS device at the screen, and could probably be pitched as a productivity/collaboration feature in this Fall's iPad-oriented iOS update.