Once upon a time, a brand's most recent Google+ post would show up in their knowledge panel when it was triggered - no more.
The SEM Post is reporting that, in a very quiet move, Google+ posts are no longer being shown when a brand is searched for and its knowledge panel is triggered. According to them, it's true for users who are logged out and logged in to Google+, and they're removed even if you follow that brand. There are some specific circumstances where a most recent post will appear - but they're awfully specific.
The benefit of having your most recent post show up in knowledge panels was that brands could show images or even animated gifs in this section to get the attention of searchers. It also made the knowlege panel bigger, and I mean hey - who would turn down free real estate?
There's been several changes to Google+ over the past few months. Google Photos has been split off from it, for example, and in order to even log in you need to access a sub menu. The SEM Post calls this latest feature "one of the primary reasons many brands were active on Google+." So the implication seems to be that there's no reason for them to post there any longer. And if brands aren't posting there, that's a short step away from the service becoming even more of a dead zone than before.
The communities still seem to be active though. So for your every day user, this might not have any impact at all.