Reading your post I came up with an idea that would give better quality cds. It's so obvious, I'm surprised no-one has tried it yet. Put Losslessly compressed music on a cd. This way you save about 40-50% space, which could be used for higher resolution, better quality files like 24 bit-96 HZ.
It may be obvious, but the endless Cyrus threads of late have shown that people expect to be able to hurl any music disc in a CD player and have it work, and there's no point coming up with a format incompatible with all the CD players already in use worldwide.
That's arguably why SACD is still around while DVD-Audio has all but vanished - music retailers didn't want to stock a music fiormat unable to be played in existing players, as they would get masses of discs being returned by confused consumers, when a hybrid system at least ensured back-compatibility.
So a disc format such as you suggest may work for home-burning by cognoscenti, but is a non-starter as a commercial product. And of course mass-market consumers are also less than concerned about 24/96 sound quality - they're more than happy with CD quality, as is clear from the masses of them using high-compression MP3 or other formats for their listening.
Back in the 1980s - "Home Taping is Killing Music". It was illegal then to hold a backup copy as far as the BPI were concerned, never mind hold a bootleg LP of a gig ( *cough* ), luckily the law had a different view. The idea of downloading music and then going out and buying is fine by me.
As for SACD, in fact, this applies to any disc, the more care taken over the mastering and engineering of the disc, the better it will sound. Being on SACD is no guarantee of anything if the production process was a duffer and moreso the mastering.
If you want to hear a good SACD, snag yourself a copy of Mark Knopfler's Shangri-La - stunning. Really shows off what the format can do. Where SACD fell down was the manufacturers and labels failing to work together to produce something the listening public could really get a hold of and understand what it was all about. Had SACD had half as much of the marketing effort DVD originally had with a steady stream of titles coming from the record companies, it'd have been a roaring success.
As it is, we have CD - it too can be excellent and will be a dominant format for a while to come. As has already been said, people like to hold on to a physical product, hence why I still buy vinyl and CD. Downloading has a place, but barely scratches the surface for me (I think maybe 50 tracks to date?). Give me Wolfgang's Vault anyday! That's a far more interesting proposition!