In On What Media Should I Backup My Photos, I recommended archiving to DVD+Rs, and discussed the issue of whether these discs are stable enough for long-time storage. Philip Peters wrote me and brought up another issue: Will we have drives that can read DVDs in ten, 20, or 50 years?
It's impossible to say with complete confidence what present-day media will be supported by readily-available hardware when our grandchildren have grandchildren. But we can make educated guesses. And I'm guessing that DVDs and CDs will be readable, with some moderate investment, for a very long time to come.
When a medium has enjoyed wide consumer popularity for a significant amount of time, the market for players stays alive for decades. You can no longer assume that every home has a floppy drive, phonograph, or cassette player, but you'll have no trouble buying these devices--all brand new. In fact, you can buy them with USB ports, which you couldn't do when these types of media were popular.
Of course, if a medium was popular only briefly, never enjoyed wide popularity, or was entirely controlled by one company, finding a player decades later becomes more of a challenge. To my knowledge, no one is making Laserdisc players or Bernoulli Box drives. You can still buy used ones, but eventually these will disappear.
Contributing Editor Lincoln Spector writes about technology and cinema. Email your tech questions to him at firstname.lastname@example.org, or post them to a community of helpful folks on the PCW Answer Line forum. Follow Lincoln on Twitter, or subscribe to the Answer Line newsletter, e-mailed weekly.