Mr. Shefter and his associates do not contend that films are actually on the verge of becoming quite that ephemeral. But they do see difficulties and trends that could point many movies or the source material associated with them toward “digital extinction” over a relatively short span of years, unless something changes.

At present, a copy of virtually all studio movies  even those like “Click” or “Miami Vice” that are shot using digital processes  is being stored in film format, protecting the finished product for 100 years or more. For film aficionados, the current practice is already less than perfect. Regardless of how they are shot, most pictures are edited digitally, and then a digital master is transferred to film, which can result in an image of lower quality than a pure film process  and this is what becomes stored for the ages.

But over the next couple of decades, archivists reason, the conversion of theaters to digital projection will sharply reduce the overall demand for film, eventually making it a sunset market for the main manufacturers, Kodak, Fujifilm and Agfa. At that point, pure digital storage will become the norm, bringing with it a whole set of problems that never troubled film.

To begin with, the hardware and storage media  magnetic tapes, disks, whatever  on which a film is encoded are much less enduring than good old film. If not operated occasionally, a hard drive will freeze up in as little as two years. Similarly, DVDs tend to degrade: according to the report, only half of a collection of disks can be expected to last for 15 years, not a reassuring prospect to those who think about centuries. Digital audiotape, it was discovered, tends to hit a “brick wall” when it degrades. While conventional tape becomes scratchy, the digital variety becomes unreadable.

DIFFICULTIES of that sort are compounded by constant change in technology. As one generation of digital magic replaces the next, archived materials must be repeatedly “migrated” to the new format, or risk becoming unreadable. Thus, NASA scientists found in 1999 that they were unable to read digital data saved from a Viking space probe in 1975; the format had long been obsolete.

All of that makes digital archiving a dynamic rather than static process, and one that costs far more than studios have been accustomed to paying in the past  no small matter, given that movie companies rely on their libraries for about one-third of their $36 billion in annual revenue, according to a recent assessment by the research service Global Media Intelligence.

“It’s been in the air since we started talking about doing things digitally,” Chris Cookson, president of Warner’s technical operations and chief technology officer, said of the archiving quandary.