The thing is, I can't think of a single person in the tech press who's actually active
on G+ who ever says Google+ is doomed or needs to be saved. This stuff almost always comes from writers who do nothing here or who do nothing except post links to their posts at their sites. Or writers who were active at first and then became like that. If all you do on Google+ is post links to your outside posts, you're simply not going to get much engagement, largely because it feels to the active users like you're either A) using G+ to try and get pageviews (certainly not
saying that's you because it clearly isn't) or B) 'testing' for signs of life at G+ like you are with this post. Those of us who actively use G+ know that it's bustling. In fact, I have to trim my circles (though I only really have one that matters) all the time. I can't keep up.
Pinterest+Google might be interesting, but with all due respect, your post isn't likely to get much more than a "this guy doesn't get it" from the G+ community, because, again, no-one who's active here thinks it needs saving. They're too busy sharing and discovering.