The problem isn't the JPEG file format, it's the media the JPEG files are stored on. If your child finds an old CD or USB drive of yours 50 years from now, they're not likely to be able to retrieve any data from it (just like you can't read a DECtape today). And the on-line services that you store your photos on today are not likely to be around in 50 years either. For your JPEG file to survive, you'd have to actively keep on transferring it from one medium or service to another.
> For your JPEG file to survive, you'd have to actively keep on transferring it from one medium or service to another.
Or go through all of the steps I outlined above. I'm hoping to do both. Well, actually, I need to upgrade to a pigment printer. I have Canon's prosumer Pro-100 right now, and would love to pick up the -10 or -1 at some point.
But the images I really care about are all shot on medium format black and white film, Fuji Acros 100, which I develop, scan, and print[1] from myself.
[1] i.e. both silver gelatin on fiber in the darkroom, and inkjet on fiber as needed.
