Feasible to apply image "interlacing" concept to video streaming for smoother buffering?
Such a concept exists, for example in MPEG-4 Scalable Video Coding. It's complicated, it comes at a cost in coding efficiency (quality/bitrate), and I don't know of anything that supports it. However it's an area of active research and it might be the way of the future. Given the current state of the art, it's a lot more practical just to do multiple transcodes, segment, and switch between them.