No... The Wii "bubble" is nowhere near bursting. Here's why
The Wii has yet to have a SINGLE pricecut in any reigon. This would certainly boost Wii sales.
There also has been no additional colors released which should definetly kept boost sales, especially in Japan.
Monster Hunter 3 and DQX.. These games alone will single handedly carry the Wii in Japan for months.
Games Like NSMB Wii and Mario Galaxy 2, and the inevitable new Zelda will keep sales of the console high worldwide. Wii is still selling very strongly in all areas but Japan, which simply has a drought in new Wii games atm. But once this changes, things should return to normal.