I might be wrong too. Most people I know went directly from Zip/Jaz to CD-R. This was when I worked at a small computer company. It could very well be what we pushed.
That is true; many business jumped on the CDR/RW as soon as possible as Zip Drives were a nightmare between the 'click of death', outrageous pricing, smaller size, and slower speed (many of them were LPT). So it may have been what killed it; undoubtedly it had a major impact on ending the popularity of the Zip and numerous other storage systems. It seems like products designed to replace or exist with the CD either failed outright or just never caught on; the advent of inexpensive flash based memory definitely has gotten ridiculously popular and is really the only huge storage success since the CD.
I would say the flash drive kill off Zip drives. CD-R were to slow and could really not be reused multiple times over and were fairly costly for limit use. It was over a dollar per CD-Rat that point of time.
Zip Disks were much more expensive than a dollar a disk and Zip disks could not hold nearly as much as the CD. Most external Zip Drives were LPT driven well into the age of USB1/2.
Indeed though the flash drive was the end-all of Zip and related technologies. The higher capacity Zip Drive held 250MB; today's higher capacity USB drives hold over 250GB with a 500GB flash drive coming our way.