As technologies proliferate and evolve, many of them become forgotten and for all practical purposes lost. The equipment and/or expertise needed to handle any particular format will become ever more scarce as time goes by, making it increasingly difficult--and eventually impossible--to access the data originally stored on the medium.
This is not accurate. No technology since the invention of the first computer has ever been lost. Not one. And even if a particular piece of equipment disappears the knowledge of how to make it does not. And given a sufficient incentive, it can be re-created. Any format can be recovered, any media can be read. Nothing has disappeared. And I'm pretty sure nothing ever will.