I have read on other forums that some developers in the future will probably make the games require the hard drive and or an internet connection in the future for the best possible playing experience.
Disc 2, or 3 etc... gets a pre-install to avoid disc swaps as long as disc 1 is in the tray.
Other ways I've heard they are looking into saving space is if the game is connected to the internet it would stream the cut scenes similar to how xbox live has the instant playback previews, not connected you may not get cut scenes. Another possibility especially with a game like GTA that has hundreds of songs for background music they would stream the music and the actual disc would contain a very small number of tracks for off line use.








