Sorry to stay on this, but another thought struck me today (that's a lot of them in one week!
If you think about it, Microsoft and Nintendo, as it now stands, have stepped out of the traditional console cycle. Microsoft released the 360 in 2005, and won't release the successor until 2013. In Christmas shopping seasons, that is 8 seasons on one platform, before you even replace it. That is a long time backing the one and only horse. Even systems that have had really long life spans (the 2600, PS1, etc) have been replaced after five or six Christmases (I prefer to think of them this way, as that is when most of the companies' promotions happen). Even the mighty NES came out here in 1985 and was sharing shelf space with the SNES 7 years later, and the same thing with the PS2 with only 7 years alone as well. Most systems were replaced even quicker (PS1 1995 - PS2 2000; Master System 1986 - Genesis 1989, etc). And unlike the PS2-PS3 transition, or the NES - SNES one, Microsoft released no portable system in the meantime. They did a hardware launch in 2005, and no more until 2013. That's a big deal.
Meanwhile, the Wii and now Wii U released at about average between console times. The Gamecube and Wii were replaced exactly when you would expect. However, with both the release of the Wii and (likely) the Wii U, Nintendo released new hardware that was actually full of fairly old graphical technology. They release a "this gen" system, just as the world moves on to the next graphical generation. (The DS and to an extent 3DS also do this). This has allowed them to step out of the traditional cycle in that they can release a system without worrying about the other guys' specs. They can still release a new system every five or six years, but over time, that can lead to them releasing all alone, and slightly more frequently than the others. When the other guys' specs don't matter to you, you also don't have to worry about their release dates.
Where does this leave Sony? They released a year AFTER the 360, and according to a lot of reports are looking to release now AHEAD of the 720. That leaves them the traditional length of a life cycle, while also trying to compete for graphics. To me, that seems like a way to box yourself into a small niche.
Want a new cheap to buy system, with a new (and I mean this in the best way) gimmick attached every 5 or 6 years? Buy Nintendo. Want a long lived system that won't be replaced for years? Go Microsoft. Want... um... an expensive system to be replaced in five or six years? No?
Again, this is just silly armchair CEO stuff from me, but it strikes me that, if Sony really is aiming to replace the PS3 that early, they are the only ones still playing a game no one else seems to like. I can't help thinking there must be a reason the other companies decided that was no longer a viable option.