I was a mac person. Mac II, MacII FX. They hardly killed the 5.25 inch drive. You might as well say the original PC killed the 8inch disk. It's always been a battle of price point issues vs usability issues.
When the Iomega Zip disk came out it was easy to see that existing magnetic media wasn't meeting the need. Optical is still hitting a good price performance spot, that may go but not because anything apple does. Just shifting of costs in flash and hard drives. You can get external HDs for roughly 25$/terrabyte and flash drives are down to 25 cents/gig. Flash at 10 cents a gig will destroy dvd r, HD at current levels is already far superior for large applications