OK, you want to push Google+? Isn't google+ supposed to be a platform (and not simply an application). Let google reader be an application on top of the Google+ platform.
i.e. facebook is valuable because people share things on it. Why would you kill an app that is causing people to share things with each other. Leverage that user base.
Reader should have simply been one app built on top of the Google+ platform. Yes, this would involve rewriting it to some extent, but better to do things that maintain your user base, than do things that give people reason to leave.
Google has repeated this error over and over again since then, especially with their chat/messaging strategies. Don't give people reasons to jump ship. If you force them to migrate to something new, they can just as easily migrate away from you.