I think the thing about used games is that you'd have to see a rise of sites like GoG before they could be ruled out as a medium. I certainly think the real concern is sales of recent releases as used games, the problem is that the current approach is a bulldozer doing the job of a crafting knife.
Maybe it would be a good idea to go the route of, similar to headdies' suggestion, a certain period of time after the game goes out of print, the license can be leased and re-published by companies such as GoG. That seems the best way to keep everyone happy, companies still see a small royalty from old games they do not produce any more but there is still a demand for, and users get their older games at used game prices, whilst the need for a used game market is greatly reduced.
