I think the impact will be bigger depending on what games will come out next year and on the release date of Wii U.
A 99€/$ Wii is pretty atractive for families who will give their sons their first console or gamers who would like to try some Wii games but wouldn`t before because the price was too high for their expectations.
Wii`s 99€/$ strength will also lie on how good the packages are: good games, 2 controllers, more colors.
If Wii U gets released around June it will be hard to decide when to cut it`s price. Before it, Wii U, being the new console, could cut into it`s sales; after it, could harm Wii U`s Christmas a little bit.
If it`s released more around September, a price cut in March, April would give it enough time to increase sales without having to fight a new console.
Let`s see what Nintendo and 3rd parties plan to release next year.