Yeah well...I've got a few CDs that are almost 30 years old and they are fine. I have about 1000 more that are of lesser vintage and I've not once seen a single issue of bit rot. As far as I'm concerned the shit is good forever.
Laserdisc collectors are quite familiar with rot since LDs are two CD-like discs glued together. Imperfections in the gluing process are what cause oxidation and what eventually leads to rot. Its the reflective aluminum later that oxidizes and this can only happen if there are impurities in the laquer top coat (CD) or glue (LD) that allow the oxidation to continue for years after manufacture. Oxygen in atmosphere as little to no effect since the aluminum in the disc is completely sealed. the Certain types of discs from certain factories are especially prone to rot, and others aren't. Conventional wisdom these days is that if a disc is ever going to rot, the causes for it were in place at the factory. It may take years to manifest, but it the rot was unavoidable from the point the defective disc was make. Aside from extreme heat/cold cases there really isn't anything you can do to cause or prevent rot. I'm inclined to believe the same thing is true of CDs. Additionally, rot in CDs is at least 1000 times as rare as rot in LDs.
If rot was ever going to effect PC Engine games, for example, some of which are as much as 23 years old, we would have seen at least a couple of rotters by now. I've never heard of a single one.