https://www.theverge.com/2018/5/8/17314524/google-assistant-update-new-features-announced-io-2018

Google made multiple major announcements related to the future of its Assistant today, including new voices, a feature to teach kids good manners, the ability to continue conversations, and Assistant being able to make phone calls on a user’s behalf.

Google CEO Sundar Pichai says he wants Assistant to be “natural and comfortable to talk to.” As such, users can now keep a conversation going with Assistant without repeatedly saying, “Hey Google,” to start every query. If you want to ask a question, you can keep asking more until you’ve reached a natural stopping point in the conversation. The feature, called continued conversations, should be available in the “coming weeks.” Amazon’s Alexa assistant already does this with its follow-up mode.