Poker remains unsolved (except for 2-player "Heads-up" limit hold'em[1]). Poker has many different variations and a player's strategy can change significantly based on many factors. The University of Alberta Computer Poker Research Group has already used counterfactual regret minimization in their Cepheus AI. I wonder if they could work with DeepMind to apply some of the techniques used in AlphaGo to poker.

[1]: http://science.sciencemag.org/content/347/6218/145