Sony (or somebody else) still makes blank MiniDiscs?
Also, isn’t it possible to use HiMD mode on "SD discs"? I never had an HiMD recorder, but I remember reading that e.g. using the mass storage functionality was possible on legacy disks as well.
HiMD gear is rare and expensive compared to the regular MD and MDLP stuff. Yes, you can use the HiMD format on a regular MD disc via a HiMD recorder, but then you can only use that disc in a HiMD unit. To me it's not worth it as the vast majority of available hardware is not HiMD. I have an MD boombox, component hifi, and a few portable players. I use them regularly. None support HiMD. If you want to get into MD you will find MDLP models and media easily and can jump right in. Not so much with the HiMD units and media.
I love that Sony keeps the optical formats alive. They "recently"(in 2018) released the one and only quad layer BDXL writable disc, with 128GB capacity. It's japan-only but the fact that it exists at all is a miracle. Even though the BDXL 128GB spec was written all the way back in 2010, no one bothered to invest in the chemistry and the production line for these, but Sony finally did, and they are still making them. I got a bunch imported from Japan, I just find it so cool.
I think the story here is that Japanese gov't and many companies still use the media for a number of reasons. Kinda like floppies still being used sparsely by the military.
Also, isn’t it possible to use HiMD mode on "SD discs"? I never had an HiMD recorder, but I remember reading that e.g. using the mass storage functionality was possible on legacy disks as well.