I can't wait to see how far DeepMind can go in this area. I was initially skeptical that AlphaGo could defeat top human players, but then it happened. Who knows, perhaps one day AI can compete against progamers in GSL!
Who do you mean by "the best humans"? I've never heard of top-tier progamers such as Flash, Jaedong, Bisu, etc. losing to AI. In fact, I doubt any B-teamer or above would lose to an AI in a Bo3.