This is going to be awesome/terrible for social engineering attacks. We'll be training millions of people to to trust phone calls from "Google". But are you talking to Google-calling-on-behalf-of-your-boss, or Google-calling-on-behalf-of-some-phisher? Or better yet, some custom system that pretends to be Google over the phone? Who knows!
At least in the demo, the system didn't identify itself as a bot. It pretended (fairly convincingly) to just be a person, and seemed focused on interactions (making a restaurant reservation, etc.) that don't involve someone recognizing your voice. In other words, I don't think the attack surface is any different than situations where you could just place the call yourself, save perhaps for the possibility of scaling…
Restaurants make or break on one or two nights in a month. A calculated social engineering attack like this could bring down hundreds of restaurants in a city, which would cause millions of dollars in lost taxes, and you see where this is going.