To be honest I also hope the PS2 stays the best selling console and the WII won't reached it, as the PS2 ruled in every genre. WII doesn't and most likely never will.
And to say that the WII has expended the market, you're wrong, the PS2 already did with its Eye Toy games, Singstar, Guitar Hero and stuff long before the WII did.
Um you do realize that none of those became a sucess except guitar hero. And guitar hero had nothing to do with the ps2 specifically except being released on it. Also montana already showed prove that the market didn't expand significantly, because the ps2 sales weren't that much pass the ps1s, and the market didn't increase that much compared to the previous generation. The wii is expanding the market more with games such as wii fit, and wii sport becoming very successful, and people such as grand parents and parents getting into gaming. The ds also did this.