I think SMcc1887 above seems on the mark, next gen I don't think there will be much change in what Son'y does. An upgraded Blu-Ray drive and Cell and more Ram is all that is needed, no establishing a new format as Blu-ray capacity will cover that. Improved and more stable/smaller Cells as well.
PS4 might be half the size of the PS3 and twice as powerful.
Hmm, pie.