While the effective life of a console is typically about six years, many companies continue to make the older systems for a couple of years after their new systems come out (assuming they were popular enough to warrant continued production). The PSOne was actually made until the beginning of 2006 (http://www.gamespot.com/news/6146549.html). With sales and profits still coming in strong, I'd give the PS2 a few more years (especially in the smaller sales regions with less income). I don't think the PS2 is really taking that many sales away from the PS3. In fact, it could be stopping people from buying an Xbox 360. And from your lips to developer's ears when it comes to Wii graphics. They need to stop porting PS2 and PSP games and put a little more work into their games. Graphics aren't everything, but there's no excuse for some of the crap we've been seeing.
Numbers are like people. Torture them enough and you can get them to say anything you want.
VGChartz Resident Thread Killer