The Wii actually helped the PS2 to live... 
I don't see the PS2 dying until 2009, 2010, meaning we will get ports on both plateforms until then.
It's also a part of Sony's strategie : good old PS2 "countering" a bit the Wii, while PS2 games not paying supported by PS3 make the PS2 even more alive.
Until 2009-2010 when PS3 is wide spread and Sony will go for the kill.







