They will disappear and all will be lost. You'll need to use another social media site to start over. Google + was basically designed to bring people and companies together. This was a network similar to Facebook and Google tried their own version. They basically give you many of the same options as Facebook, with one minor exception, you'll need a Google account to access this site.
If Google wants to keep this site opened they will need to moderate and clean it up. When people are left on their own to post and add whatever they want without any control this is what you get in the end. Anyone found violating the terms of service agreement should have their accounts shut down and banned from the site. There should be a reporting method in place where anyone can report such a violator and Google will take the actions necessary to correct this problem.