During the 1990s, there was a boom in the sale of CDs. A significant part of this boom was due to the "CD replacement cycle," during which many people replaced their old vinyl LPs with new CDs. These were essentially freebie sales for the recording industry, which was able to make a quick buck by transitioning their back catalogs to CD. The good times couldn't last, of course, and CD sales declined, in large part because the replacement cycle ended. See, among others, BBC News (Stopping the Pop-Swappers).

So, where are we in the DVD replacement cycle? DVD has pretty much wiped out VHS and there are many who are replacing VHS libraries with DVDs, which is probably having a very nice effect on Hollywood's bottomline. Additionally, there is a big sale of back catalog stuff, particularly old television shows that were never released on VHS. Eventually, however, these good times are going to have to end. The question is, how far away is this? How big will the drop be? And, how much will the MPAA blame on copyright infringement?