Tape is a great medium for reliable backup of larger data volumes for corporate users, and I believe it will continue to be so for a long time.
For backing up your personal workstation(s) at home tape has been gradually replaced by cdrw and later by dvd±rw. Tape drives for personal backup have not been able to keep up with the growth of disk capacity. Up until the later 90's one could buy reasonably priced tape drives and simply dump the content of ones entire hard drive onto a single cartridge. Unfortunately, todays tape drives that can do that are not priced for the consumer marked.
PS! My six year old Iomega Ditto is still serving its purpose!