I checked some sources about this AV1 codec it's having heavy usage of processing power during encoding and decoding, much higher than h.265. With almost 30% better compression.YT already uses a comparable codec called VP9.
The reason h.265 isn't everywhere is because it is not free to use and requires royalty to be paid to MPEG LA compared to VP9 which is free. Also, there is a successor to VP9 coming soon called AV1 codec and it is again going to bring large improvements over VP9/ h265.
Even h. 264 has royalties as far as I have read (maybe I'm wrong).
I really wish h265 is open codec.
Cuz Google had to go through lot of work around to make it get around h 265 codec without having INFRINGEMENT With the same . I guess the codec is developed (not sure) but might be waiting for people to have much more better chip for encoding and decoding purpose.
The use case scenario is tremendous to be honest..
I can stream a 720p (not 720p60) video without buffering if I don't skip forward with a 2mbps conn. Imagine if I could do the same with 1080p, or 2k(might be an exaggeration
A video describing the same.
Source