No, you can't. Read up on the old threads about compression. It has limits that are often overlooked by advocates of DVD over HD formats, who's argument forgets the fact that pretty much everything is already compressed. A 12 GB BRD games is also compressed!
The key area to reduce disc requirements seems to be procedural generation (other than less content ) which still hasn't progressed very far beyond random dungeons (and incidently the random dungeons of CON increased it's requirements. CON1 with random dungeons was dual layer. The sequel was single layer because they for-went the random dungeons). If DVDs don't get limited, IMO it'll be because devs don't want to spend out on creating that much content, rather than the games being larger and yet squeezed onto DVDs using Clever Tricks. Though I'd be very pleased if procedural content takes off and it's more content created on that fly that reduces the need for storage capacity. That'll have the added benefit of adding more diversity to games, such as characters being one standard model loaded from disc with variations applied (think Tiger Woods Golf avatars) for 100 different characters in the city, rather than 10 models loaded from disc and repeated.