That however shall never be an issue. You can still open, today, old obscure formats from the DOS days. Even custom ones only use by a very select few software

That however shall never be an issue. You can still open, today, old obscure formats from the DOS days. Even custom ones only use by a very select few software back then. Certainly not true. One example: I have many thousands of photos from my Sony digital camera that cannot be opened by any current operating system without installing third-party software. I'm lucky that the camera also output JPEG versions as it saved, so I'm able to view the JEPG thumbnails, then drag the Sony version into my photo editor of choice.