Dodece makes several excellent points.
Also consider the effect of 3rd party companies. They've invested considerable time and money now developing for the PS3, ultimately they'd port to 360 to recoop cost, but they'd still lose a lot of invested money because they'd never reach the expected install base on PS3. They'd be less willing to develop for Sony in future.
Sega did this (let a console 'die') with the 32x (I believe, someone correct me if I'm wrong) to similar results.







