Today Google announced a brand-new feature for Gmail called Smart Reply. It's basically like predictive typing for email and message replies.
Smart Reply works pretty straightforwardly. It uses Google machine learning to suggest three responses to the emails and messages you receive. You can ignore them, or you can pick one and then hit send, or you can add additional text if you like. The more you use Smart Reply, the better the suggestions you'll get.
Inbox by Gmail and have had Smart Reply for a while. Google cites that 12 percent of replies sent from Inbox for mobile came from Smart Reply.
For more about Smart Reply check out Google's Blog.