This is another step in the overall move towards full digital distribution. Unless they're on XNA, I think the days of 400 Xbux games are coming to an end.
- xbox originals
- get people used to fully installing games on the hard drive with the Fall update; also provides a temp fix for future problems with DVD space issues
- ease into lengthier games costing more Xbux, roll out larger hard drives
Sony's doing the same thing, at a different rate. I think by the end of this console cycle you'll see $30-50 "full" games (Sony's already tested this with Siren), and when the next gen starts I believe the split will be along the lines of 60/40 between downloadable and boxed retail games. Possibly, you'll be able to choose between paying $60 for a disc & box version of a game, or a $50 Steam-like "pre-download" which you can download when a game "goes gold" and which will activate on a game's release day.