Trying to determine what file format(s) will be in use even 10 years from now is not possible. Having seen changes in file formats over the years I can also say that conversion programs have kept up with it. In the event of camera systems that are now gone, Contax 645 for me with an incredibly obsolete Kodak digital back, the original raw files are still editable in Adobe and Capture One software. No doubt in other software I don't have as well. At any time I can press a button and convert to a current format. As long as you are aware and check with new versions of software for compatibility there is no reason, nor excuse, that the files can not be migrated to new formats to keep up with changes.
Negatives and prints are not forever either. The emulsions and print media do degrade, chemical reactions continue which change colours, storage conditions are seldom ideal, fires and floods happen, people throw out old boxes when cleaning up estates.
All you can do is deal with it as it evolves and not obsess with future proofing which you can't do anyways.
For orphaned video files I would suggest checking out the converters from NCH and DVD Video Soft if you don't have access to PremierePro or other video editing software. I know other folks who didn't keep on top of format changes, video has been rather bad for that, and were able to convert successfully.