One on hand: the dropping price and reliability of flash memory may make this possible, with the first one to use it for a home system either being Nintendo or Microsoft.

On the other: Blu-Ray discs have higher memory storage than flash-based media right now and have better scratch-proofing, meaning that they would be an ideal media for the next generation. After the next, we may see a major usage of flash-based, with digital distribution secondary to it.