The way I see it, the biggest opportunities for the foreseeable future are VR and tools that leverage deep learning to enable unskilled people to produce high quality creative works (e.g. neural drawing, neural music making, neural writing, etc). Doing a side project in either of these areas is more likely to lead to something revolutionary, and even if you fail your job prospects will be greatly improved. On the other hand, both of these areas are hard, but in life, nothing ventured, nothing gained.