Li-Fi is relatively new, but as you could probably guess by the name, it uses light pulses to transmit data. It could be a long-term replacement to ubiquitous Wi-Fi protocol. AppleInsider has more about how Li-Fi works:
Li-Fi works in a way not entirely unlike a traditional infrared remote control. Data is transmitted by rapidly modulating a light source, and received with a light sensor before being reassembled into an electronic signal.
Unlike your television remote, Li-Fi uses visible light and the modulation happens in a manner imperceptible to the human eye: that means the same bulb that lights your hallway can act as a data access point. It’s also much faster, with theoretical throughput capacity of up to 224 gigabits per second.
Just to put that number in perspective, the fastest theoretical output of 802.11ac Wi-Fi is 7 gigabits per second.
Its unknown when or if Li-Fi will ever be introduced in an Apple product. But with Apple actively testing out the technology in current versions of iOS, the company seems to be actively exploringnew ways to transfer data. The future looks bright, literally.