Given these challenges and the very low usage of the consumer version of Google+, we decided to sunset the consumer version of Google+.
Also, this bit:
At the same time, we have many enterprise customers who are finding great value in using Google+ within their companies. Our review showed that Google+ is better suited as an enterprise product where co-workers can engage in internal discussions on a secure corporate social network.
Remember Google Buzz? It was a way to have internal discussions inside of an organization and it worked really well within Gmail. It sounds like Google+ will no go back, in a way, to being what Buzz could/should have been. I think because Google themselves used Google+ they may continue to keep it around for a while.
A reminder, as I've said before, if you use anything Google makes that isn't Adwords be prepared to wake up one day and read that they've decided to stop supporting it. Put a backup plan in place now to help with that. As an example, I use Google Photos every single day, but it is not my primary photo library or storage solution.