I've been talking about ETC1S for several years. I removed some of my earlier posts (to prevent others from stealing our work - which does happen) but they are here:
https://web.archive.org/web/
https://web.archive.org/web/
We also covered our work with ETC1S and a universal texture format at CppCon 2016:
Just in case there's any confusion, we shipped our first ETC1S encoder to Netflix early last year, and developed all the universal stuff from 2016-early 2018.