How does system pricing compare to the high capacity tape systems? I view this as their actual long term market. A solid state device would be better, but disk is probably ahead on retention length at the moment.
It is clearly not as easy to pull a tray as a tape cartridge. On the other hand, tape (optical) machine formats and drives tend to go away after a bit as new versions appear or companies go out of business. The formats of the standard hard disk should survive much longer. Or, since they are well known and public, can be easily addressed in the future. Worse comes to worst, you can probably find something to read a current hard disk pretty far into the future.
Let us ignore for this discussion the actual need to keep many of these records forever. Tends to be driven by logically faulty laws.
When I was working, I did document imaging systems for the last 10 years or so of my working life. A really big issue (generally not shared by sales with the customers) is the obsoleting of optical disk formats. Some were proprietary formats or actual proprietary single source hardware. Your system breaks, company has gone out of business or no longer supports this stuff - your store of data to keep forever; ain't there any more.
Micro-(insert name of level of technology) film records are the only things that tend to be immune to format changes. They have some longevity issues; but can be minimized by expensive storage. Generally you can still read a microfiche from the late Roman empire if you can get a viable copy. No hardware or format issues.
This is one of the areas that I do not see being addressed in a rational way. Get past the stupidity of saving much of this stuff forever, there needs to be a way to deal with things that really need to be preserved. We can safely start deleting the building entrance logs from the 20's by now. How many billions of these things are eating trees and some form of electronic storage and accomplishing nothing. Particularly under the normal circumstances of not validating ID. Damn I hate the public perception of pretty much everything (e.g., making you sing in makes everyone so much safer). Particularly those things propagated by the government and large corporations.