It's sales will be completely irrelevent in 2010. (whats it doing now..no more than 40k, 50k a week?). Plus with lower prices all around form the current gen consoles, it's more appealing to get one of those than a PS2. I wouldn't be surprised if half the current PS2 weekly sales are from rebuyers.
2010 it will probably plummet below 30k a week worldwide and dwindle to nothing in 2011.