To me, your points are telling me that their lifespan will be about the same. I dont expect to buy the next iteration of the Xbox or PlayStation until 2012 at the earliest. And even then, it could only just be an upgraded version of the 360 or PS3 - like a slim version with a few new features.
Also, in terms of first party selling power, if you want to put them side by side, I dont see any mainstream >5m games for Sony whereas MS has 3. Of course GT5 or God of War 3 but that milestone wont be reached until more than 1 year away.







