Adversarial Machine Learning. Fake news detection using ML. Integrating 'good old fashioned AI' ideas with modern ML techniques - to some extent Alpha Go went in this direction. While I am glad AI has moved far more towards the machine learning direction, i suspect the decades of AI research that preceded it may come back in a form that is combined with more modern techniques in some way. I see Alpha Go (and Alpha Zero) as steps in that direction. Also, applying deep learning to search engines and making that scale efficiently. I suspect google has partly solved this already, but haven't gone public with any of the tech, but that's pure speculation.