My father told me he wanted to make USB flash drives of all the scanned and digitized family photos and other assorted letters and mementos. He planned to distribute them to all family members hoping that at least one set would survive. When I explained that they ought to be recipes to new media every N number of years or risk deteriorating or becoming unreadable (like a floppy disk when you have no floppy drive), he was genuinely shocked. He lost interest in the project that he’d thought was so bullet proof.
Microfilms used to be sold as having a life expectancy of up 500 years. But in my experience they were a pain to use and the machines costly to maintain. The films would tear regularly too. Also the quality of the recorded image could be very poor sometimes.