I don’t doubt we’ll be able to read JPG files basically forever. I do doubt that most of these files will survive media degradation/damage/loss, and (in the case of cloud storage) account loss and corporate restructuring/bankruptcy.
In other words, if you want your images to be viewed by future generations, start planning now. The simplest solution is just to print the best ones in book form and give copies to friends and relatives.
I can’t see that happening. Everything can still read bitmap and that’s been a somewhat obsolete picture format for a couple of decades. Pictures are easy. Video is problematic given the complexity of the formats. Although I haven’t run into a situation where an old video will not play on a modern machine. I’m talking MS Video 1 encoded, circa 1995. You’ll end up having more obsolescence with your media and hardware than with the decoding of the files that are on it (assuming it’s a somewhat generic format).
Since this as been forked, I’ll add this comment. Digital media permanence really isn’t much different that any other permanence when that media is important to you. All digital media degrades and dies, but then so do physical things like books, tapes, records, ect… If you want those physical objects to last you take care to preserve them. If you want your digital media to exist into the future you just make copies of it. DVD’s degrade, so you rip those to a HDD or a media of your choosing.
As far as formats go, unless you are dealing with something that was already not widespread or barely supported, I think it’s a rather moot point. Programs like FFMPEG have decoders that can support all popular formats since the mid 90s. Now I do have a few “video” files that I only ever came across from back in the BBS days. Are they important, no, but they do represent a file format that never really gained traction and that decoders are not common for. If I really cared enough I could have converted them over to some common format along the way and for all intents and purposes they would have been “preserved”.
And if you are looking at this in +100 year time spans then my same argument applies. Youtube has black and white silent movies that are near 100 years old.
Again, all this comes back to how important the media is to you… My wife doesn’t care about my Farscape DVD collection, but you can be sure they are all ripped to an external hard drive.