Imo the tapes are best long term storage medium. You can easly get around 25 years of storage from a tape. Unfortunately streamers are expensive and hard to use. I always toyed about buying a streamer for my data... Ended up hoarding HDDs...
But if we speak about 100s of years.. Hmmm, unsolved stuff..
I have a complicated relationship with LTO, QIC and QIC mini. Mostly it works but it senses fear like printers …