b122251 said:

instead of needing proprietary software to play in the first place. I personally was very determined in storing these preservations in a way that will last, so I burned these mkv files on an M-Disc blu-ray, together with eleven different checksums, separate subtitle files and some other related files. I think .mkv files will be readable long after blu-ray video has stopped being the standard. Right now playing a blu-ray video on a computer is already difficult and often requires proprietary software. Also it'll probably be a lot easier to convert mkv files to some future standard years from now, than ripping a blu-ray video. The only disadvantage to this method is that you have to be certain that the blu-ray player you wish to play it on supports mkv files.

I don't think you need any proprietary software for burned blurays (obviously official ones are another story). You can easily view them with VLC. You can easily navigate to the folder/file for your feature and copy it, remux it, etc.

And if/when these do end up having nice little menus and special features, a blu-ray package will be great. The menus won't be preserved by MKV alone.

Really the main downside seems to be the number of subtitle tracks. It's unfortunate. Though there are probably few people that will be affected beyond the 31 tracks used, it's still a shame as Catbus has been as comprehensive as possible and it won't be represented fully. MKVs or remuxing will be an option for them, though.