Bitcoin Q&A: What are the Most Exciting Recent Developments?

: What latest developments in cryptocurrency excite you?
Payment channels and Lightning Network; balancing privacy and scaling; covenant technology, recursive constraints (Emin Gün Sirer); time-locked UTXOs; MimbleWimble; TumbleBit; ZeroCash; Segregated Witness/ SegWit. Bitcoin is an incubator for black swans. Underneath all the high-level debate about block size, the innovation has been accelerating for two years.