Regarding degradation: CD-Rs degrade because you write them by using a laser to effect chemical changes, and the chemicals can break down. Commercially-produced CDs, on the other hand, are pressed; they are physically molded by being pressed against a "glass master", and the physical pits are much more durable. Making the glass master is expensive, but the incremental cost of pressing is tiny compared to burning CDs.
So, if you could figure out a way to etch CDs instead of burning them, or make the pressing process cheap enough, you could make very durable CDs. Or if you want to make lots of durable copies of one CD, you can do that now with a glass master.
It sounds like it is possible to make longer lasting CDs using a glass master, but it is only practical if I am making lots of copies. So, for purely archival purposes, optical media doesn't really have a process for extending longevity.
That's why I write all my crucial data onto stone tablets.
The write speed and data density are terrible, the drive, media and storage space cost a fortune, but dang if the data won't last a couple thousand years.
