This I heard about in one of the LongNow seminars by Clay Shirky Making Digital Durable: What Time Does to Categories (Nov 02005), which he has taken from Steward Brand's How Buildings Learn.
Basically, as described with regards to a building, there are different speeds of change for different layers: the interior of building changes faster than the colors of the wall, the walls themselves faster than the core, the core faster than the site etc. So there are multiple layers, all having different rates of changes.
With regards to digital information, there is the data medium, the data format, the application, the OS, the computing infrastructure, the power system etc. So even if one is to solve the medium problem, or the format, application problem - at some layer one will have a problem.