Reading that blog post, I was surprised to learn that many modern games dedicate more than half of their filesize to textures. I haven't played an AAA game in more than a decade, but I would have thought that meshes and (particularly) audio would use up more space.
It sounds like developers are stuck between a rock and a hard place. They need one of the specific compressed pixel formats which can be efficiently read by the GPU, but those formats are about ten times larger than a similar JPEG file, they don't losslessly compress well (modulo RAD Game Tools' discoveries here), and recompressing raw pixels to a GPU-addressable format at load time would be orders-of-magnitude too slow.
RAD Game Tools' approach here is clever, but it feels like a bit of a hack. The obvious next step would be a lossy compressed image format which can decompress directly to BC7, exploiting spatial-correlation tricks similar to those which PNG uses to get better results than a gzipped BMP file. Has anybody tried this already?
I wouldn't call Oodle Texture a hack. But there's also https://github.com/BinomialLLC/crunch and https://github.com/BinomialLLC/basis_universal. The latter has the advantage that it can be decoded to multiple different compressed texture formats, so that all GPUs can be supported from a single file (different GPUs support different formats so you can't necessarily send the same compressed texture to any GPU).
Surely this exists already?