A Wii 1.5 implies a significant HW change. I would be surprised if Ninty went that way for a retail cycle of 1 yr-18 months only.
A Wii 1.1 I could see happening. It's now the least sexy looking console on the market (yes I reckon 360 phat (esp the white casing) is a fugly console, 360s is a different proposition all together), so a new case design at least is in order. Then again the DS is butt ugly compared to PSP and that didn't hurt sales one bit.
“The fundamental cause of the trouble is that in the modern world the stupid are cocksure while the intelligent are full of doubt.” - Bertrand Russell
"When the power of love overcomes the love of power, the world will know peace."
Jimi Hendrix