Floppy disks ? Really ?

If memory serves, these 8-inch floppies were replaced by 5.25-inch which in turn were replaced by 3.5-inch which are now difficult to obtain, and were replaced by USB and Flash Drives. This got me searching for a source of the 3.5-inch floppies, which are used in my Canon Starwriter 30 word processor.
That in turn got me looking for its IR-100 ribbons, and those are really scarce.
A source in the U.K. wants 21 British Pounds for one ribbon. That's $38.79 in Canadian dollars.  Canon originally sold these in a box of 3 twin-packs for 
$39.45 plus taxes and delivery, for a total of $50.90 for 6 ribbons, or $8.48 each. So those Brits have tacked on $30.00 per ribbon to the price. Luckily, I still have two boxes of six ribbons each on hand. And that's now worth about $465.48 according to those Brits' prices. Fortunately, 3.5-inch floppies are still available from Staples Office Supplies, in a pack of 10 for about $10.00 + tax.

Forgive the digressing above, please - the article prompts me to ask how long those disks can be tested for accuracy and completeness before they begin to fail mechanically or otherwise become unreliable? Several decades is a long time to be using the same stuff without having serious problems. I'd be concerned about that if those were mine. Granted, we hope it will never be necessary to use those weapons, but if it ever was, it would be much better if they worked as planned rather than malfunctioning during launch or en route to the target. Can fifty-year-old technology be trusted? Where do you find the replacement parts for it? At what cost? 

Time marches on, trampling everything underfoot.