IMO, at the moment, nothing short of an earthquake in console gaming is going to prevent the DS from outclassing the PS2. This year, Nintendo sold something like 30 M DS. The GAP is something like 20M ATM.
About the Wii, with the same timeframe since launch and the same number of christmas seasons, the Wii is at minimum 15M ahead of what the PS2 was.
In 2009, the Wii sold more than PS2 managed in its best year (2002).
Maybe we should wait a little to say that the "wii won't make it".