I really don't think the problem will be obsolete file formats. The problem is accessibility to the raw bits due to media damage and corruption. I've already had my headaches wrt that, and there have been many acrimonious debates here about this issue. Suffice it to say, whatever the advantages or disadvantages of digital vs analogue media storage, I have at my fingertips on my computer thousands of photos over 12 years old of my family. By comparison, I have only a relative handful of hard copy photos from the same time and before. Somewhere, in the basement, lies a box with thousands of slides and negatives. I will probably never look at them again. Nor will anyone else. Given the choice, I'll take the perhaps ephemeral access to the thousands of images now to the never access to the thousands somewhere in my basement.
YMMV, but that's why there are choices in the world.
/T