any source for this? as mentioned, long term digital storage is still a problem waiting for a solution, but form my experience if you let a hard drive sit around long enough, you have a pretty good chance of it not spinning up. Yes, flash overused can be a problem, but then flash is getting cheap enough to do write once read many type of uses. I think we're getting pretty close to 3d flash technology which will flip things pretty quickly, moving flash cheaper and more adopted than hard drives - the death knell of conventional spinning platter solutions.
Floppys and Magnetic Tape have the longest rated lives of most digital storage media. Flash memory is usually good for up 10 years assuming it is not cycled heavily. Spinning platter disks are usually rated for 3-5 years but that assumes constant use. The problem with them is the media will last longer, but inactivity can kill the mechanical components almost as easily as wear from spinning and head movements. You always have to be careful separating the "data storage" life from actual reasonable retrieval. A hard disk might still have data, but it might cost $1000s to get someone to crack it open and retrieve the data for you.
I know nothing about
M-Disc Technology, but have just started investigating. Waiting to see if it picks up support. It is similar to DVD/BD in that it is an optical disc, but the
claim to fame is that it uses an inorganic layer to store data and it is better sealed than DVD/BD discs. Some research suggest up 1,000 life with minimal data rot. Obviously, if accelerated aging tests can be developed and it tests out well, this will be a boon to all of us with tons of data. However, it is currently limited to 100GB BD Dual Layer BD. I'm sure those are pricey disc.