I think GTA's style of creating a big environment, filling it with content, and making you run errands within that environment can fit one disc, easily. Saints Row 3, GTA4, and Red Dead did it. I think the FMV, Dialog, and detailed characters made L.A. Noire a beast. It damn sure wasn't the side missions, music, and mini games.
Mark my words: GTA5 will be one disc on the 360.








