Google will be making some changes that will eventually require readers to have a Google Account to sign into Friend Connect and follow blogs.
As part of this plan, starting the week of January 11, they'll remove the ability for people with Twitter, Yahoo, Orkut or other OpenId providers to sign in to Google Friend Connect and follow blogs. At the same time, they'll remove non-Google Account profiles so you may see a decrease in your blog follower count.
If you use a non-Google Account to follow my blog, you need to sign up for a Google Account, and re-follow my blog. With a Google Account, you'll get blogs added to your Reading List, making it easier for you to see the latest posts and activity of the blogs you follow.
Here's the details from Google: http://buzz.blogger.com/2015/12/an-update-on-google-friend-connect.html