Hardware

One major problem with very-long-term-data-retention formats is that the hardware to read the things may not be around in a surprisingly short period of time. Like, if you assume that this format isn't bumping up against fundamental physical limits, then it will probably be supplanted down the line by something else, and people will probably stop making the devices to work with them before long. The devices to work with the media won't last as long as the media, and there probably won't be new ones produced.

https://en.wikipedia.org/wiki/BBC_Domesday_Project#Concerns_over_electronic_preservation

The BBC Domesday Project was a partnership between Acorn Computers, Philips, Logica, and the BBC (with some funding from the European Commission's ESPRIT programme) to mark the 900th anniversary of the original Domesday Book, an 11th-century census of England. It has been cited as an example of digital obsolescence on account of the physical medium used for data storage.[1][2][3][4]

This new multimedia edition of Domesday was compiled between 1984 and 1986 and published in 1986.

In 2002, concerns emerged over the potential unreadablility of the discs as computers capable of reading the format became rare and drives capable of accessing the discs even rarer.[14][15] Aside from the difficulty of emulating the original code, a major issue was that the still images had been stored on the laserdisc as single-frame analogue video, which were overlaid by the computer system's graphical interface. The project had begun years before JPEG image compression and before truecolour computer video cards had become widely available.

I think that realistically, if you want to maintain something for very long-term archival use, it's probably going to need to be rolled over into a new format periodically.