I doubt we'll still be using CD's in 10 years, so I never expected any CD's to last that 100 years. I've got several old CD-R disks that use the old cyanine dye burned with some of the earliest CD writers. They are over 5 years old, and still read fine to this day.
I've got music CD's that I burned with my first CD-RW drive, that have been in my truck for over 3 years subject to high temp and humidity, not to mention the temp changes, and they all still play just fine.
Never trust any one media for backup. The best backup is to use multiple types of media and storage. My digital pics are backed up on three different computers, and regularly backed up to DVD's. If any one fails, I still have 3 backups to restore from.
"You can either want something to be true, or you can want the truth. Pick one." - Mr. Diety