Today's (yesterdays?) "hot" things: bitcoin/blockchain/decentralized, AI/DeepNets, VR/AR, genomics/liquid-biopsy, wearables, human-machine neural lace, cloud/GPU/TPU, 3D/additive manufacturing
What's the next big thing that no one or very few people are thinking about? What feels like a toy today, people get a chuckle out of? What's a contrarian play today that looks like genius tomorrow?
It can also be a "comeback" with a twist. Very few people thought yet another messaging tool would prosper (Slack), etc. It could also be obvious.