I recently went through all my old 3.5" floppies I could find and most of them were still quite readable. This seems like a bit of hysteria to me. I didn't preserve as many of my 5.25" floppies, but I also don't have a drive for them. My 3.5" drive is an old USB one that came from a Toshiba laptop circa 2000. It was in a drive bay that was replaceable with a cdrom drive.
Anecdotal data-point: a few years ago I rescued the data off my 3.5" floppies from the early 90's (IBM PC and Atari ST formats) and they all seemed to be fine.
I don't have any hardware to read my pile to 5.25 Atari 800 disks.
Odd question, but I've always been wondering. These things just seem to hast forever.