Wow, a lot of debate. Some good arguments some a little of the mark.
Either way, when comparing consoles whether or not its handheld or topbox, you have to keep the variables of the statistic consistent and fair.
Unfortunately the OP has skewed those variables. He is comparing the lifetime sales of the PS2 of 10+ years to the Wii whom he is estimating to have a shelf life of 6 years with no more support.
Also, the sales trend, is completely the opposite of his end numbers. The Wii is still selling very well, and the PS2 has now lost a huge chunk of momentum.
However, the devils advocate to that, is that the PS2 had a huge amount of good 3rd party support to maintain its selling trend as well as some other factors.
I don't know if the Wii will surpass the PS2, it all depends on Nintendo.
What I do know, (and it isn't very much), is that these goalposts have to stop moving or at least use a reasonable and equitable set of parameters when trying to justify an argument.
Cheerio.
I game. You game. We game.
I'm a videogamer, not a fanboy, but have a special place for Nintendo.
Current Systems Owned: NSwitch/PS4/XONE/WiiU/3DS/2DS/PCGaming Rig-i7/ASUS i7 Gaming Laptop.
Previous Game Consoles: PS3/Xbox360/Wii/DSL/Pretty much every one thats been released since the Atari 2600.
