Agreed. I think the user base will continue to grow, mainly because more and more websites are adding the G+ button to get any advantage they can in SEO ranking

Agreed. I think the user base will continue to grow, mainly because more and more websites are adding the G+ button to get any advantage they can in SEO rankings, and that alone will fuel the growth over the next few months. However I'm not sure how most users will feel about associating their online activity/searches with their social network.