A while back I thought of a great business idea: buy and mothball a computer system every 2 years, and then wait 20 years. Set up shop, and offer a service to help people recover their data from media which were no longer supported by current technology.
The first computers I used had 5¼-inch floppy disk drives (that really flopped), then saw the shift to 3½-inch drives (that no longer flopped, but were still called floppy), and then the first hard drives. I saw the evolutionary dead-end that were the "super-floppies" (and even worked a temp job at Iomega's local office for a while), and then the rise of optical media, and then USB and flash drives.
Each time we crossed a threshold from one media to another, there was a brief window - a few years usually - where both systems of media existed side by side, and you could transfer data from one to the other: computers with 5¼-inch drives alongside 3½-inch drives in the mid-eighties; then 3½-inch drives with hard-drives; then a brief period where computers had hard drives, 3½-inch drives, and an Iomega Zip drive, before CD-ROMs took over, to be replaced in turn by DVDs. When Apple got rid of the floppy drive from their iMacs in favour of an optical drive, that signaled the crossing of one threshold: similarly, the lack of an optical drive in the MacBook Air signals another threshold crossed.
I found all my old photo back-ups yesterday, a thick stack of CD-ROMs. I spent today transferring them across to a hard-drive because in a few years, I don't think there will be computers with optical drives any more. Physical media aside, I wonder about the file format: besides transferring from one physical medium of storage to another, I wonder whether jpg files will be readable, or Nikon RAW files for example, will be readable.