It’s not talked about much, but flash memory does not last that long. Sure, it’s permanent storage, as long as “permanent” means 5 years of regular use. After that, the danger rises.
But, some Japanese scientists have come up with new tech that might allow for lifetimes of hundreds of years. As a bonus, the memory takes up less space, by a factor of two. And, it uses less voltage to do writes.
It’s pretty early for this announcement, however. Nobody is yet making it.
(It should also be noted, that finding a computer in a 100 years that is compatible with today’s memory is another challenge. Just try reading an 80s-era 8″ TRS-DOS diskette with a 2008 computer.)