Virtual Reality - the quality of experience is already there and a lot of talented people working on VR apps. Totally new toolchains will emerge, but game programming background gives a head-start.

Deep learning is potentially the big breakthrough in AI and ML, already big companies are doing interesting stuff with it. Mastering deep learning will give you superpowers in coming years.

Mobile. Never downplay mobile. It has changed consumer market, but it has still a lot of opportunities especially in business side. There is no silver bullet for cross platform development, thus having native dev skills for iOS or Android will still be relevant in 5 years