Lots of new USB DVD drives are available from brands I've never heard of. But the availability of Bluray drives is so low I suspect they're only new old stock.

Probably. Bluray still exists, still a popular medium for selling games on PS/Xbox and to certain extent movies to people who like to watch on their high-end equipment.

Absolutely. And discs as well. I had an x-ray recently and asked them to give me the image so I could take it to a different clinic, and they burned it onto a CD. So I suppose optical media is sort of irreplaceable for medical applications at least.