I'm sure Nintendo is planning to drop the Wii to $149. Wii Party tanking is just a sign that the Wii bubble has long since burst but I think we all knew that. Except for the insane 3 million sales in December 2009, the Wii for the past two years has normalized, sales wise. Wii Fit is almost three years old and soccer moms have long since moved onto something else. Old people are still probably playing Wii Bowling and not getting much else. In fact, I'd say the mass majority of Wiis are collecting dust, handed off to a nephew or niece, or in a box in a closet.
The PS3 doing what it is isn't surprising. Sony lost the casual market from the beginning to the Xbox 360. The obvious proof was that multiplatform sales were always 2-3x what PS3 had. Since most casual gamers will just buy what their friends own and play, it is inevitable that 360 sales would maintain and PS3 would always be struggling. Nobody gives a rat's ass about what Sony is dishing up these days. GT5 will have the console see some temporary marginal gains but it will go back to where it was in two or three months.
Edit: I too won't be surprised if Wii gets dropped in support for the 3DS. Nintendo has never really shown much respect for their fans. I could see Wii being dropped for the 3DS, first party software-wise.