Coming as an inevitable surprise to no one, Google has announced today that Hangouts On Air will be leaving Google+ and moving to YouTube Live. All future broadcasts will need to be scheduled in YouTube Live, and events in Google+ will shut down after the hard date of September 12.
Google says that recorded Hangouts On Air will still be available on YouTube, and that Google+ event content will be available in read-only format in the Activity Log.
In regards to Q&A, Google's suggestion to broadcasters is to use Slides, which has the same feature, in conjunction with broadcasts. The company also suggests that questions are gathered ahead of time via social media. However, Applause and Showcase will not be moved to YouTube Live, and Google has offered no alternatives.
This is yet another feature getting pulled out of Google+, following Photos last year. Perhaps, though, this move makes sense. Recorded broadcasts from Hangouts On Air were archived in YouTube anyway, so consolidating the broadcasting platform and the archive location seems like a smart move.