If you save all high resolution digital photos to TIFF image format, all original information is preserved forever, and can be used as a master copy for any compression you wan't later, like JPG. Copying JPG files does degrade the resolution over a short time, so I can't recommend it for original archive format.
The recording media is the next concern - because many burned DVDs only last about 5 years, so that is another way to lose quality in resolution, if not a complete loss in a disastrous way! If a person could find a professional service to "print" them to a DVD like the music industry does, then I would be confident of this archiving method, but then you'd want to keep them in a fire proof safe too! I really like wadetrek's suggestion for the Wolverine digital scanner, as I never knew they came out with a 14 mega-pixel version like that!! This is more than enough resolution to blow up original images with no more degradation that the original photo! Unfortunately, I can only trust internal magnetic hard drives for storage of such precious
memories, as I've seen too many external drives crash and burn. Perhaps an NAS with a good reputation and some RAID for file redundancy would help.
Of course it is probably way smarter to simply keep more than on source for backup, so you can use more economical media for archiving. This way, you don't need any one best technology to assure survival. Since cloud solutions have small storage room for free services. One could at least keep JPG images out there for a last ditch effort to store a facsimile of the memories. TIFF images take up a lot of room, but hard drives and flash memory are getting cheaper by the minute, but I'd never rely on flash memory alone for backup. With a magnetic hard drive, the likely hood the information will fail is zero if the hard drive is not smashed, burned, or some kind of security Guttman wipe is performed on the memory recorded there. Even if the hard drive controller died, a recovery service would always be able to recover the magnetic images. If the hard drive were simply accidentally formatted, recovery software can always solve that crisis. Professional recover services are VERY expensive, but what are your memories worth?
There again, if you have your complete archive on DVD or Blu-ray, and also on, say an SSD (flash) drive, and also on a hard drive, preferably on RAID - then any one failure could be cheaply recovered by simply copying the TIFF files from one of the other of the different backup schemes.