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Microsoft develops ultra durable glass plates that can store several TBs of data for 10000 years
(unlocked.microsoft.com)
This is a most excellent place for technology news and articles.
They were, but odds are a future generation of glass storage will be too. CDs started off as a hard WORM ROM, but eventually a rewriting process was developed. I just checked, CDs are from 1982, and CD-RW were introduced in 1997, so I would likely expect about the same turnaround of ~15 years from when these are released to the public.