The key weakness to the Wii is it isn't future proof. However given Nintendo's strategy I don't think they ever intended the Wii to be a 7-10 yr console. More than likely 4-5 yrs on top and the next 3 phasing it out as they release N6.
What I always like to call Wii is its an intermediate console for Nintendo. It's mean to disrupt the market to setup up a future console. Why do this? Well if you can all of a sudden change the market to where brand appeal is highest for you then you can release a more pricey console next gen to make more money through software and hardware. Not to mention gives you the luxury of starting earlier. But mainly about getting the Nintendo brand significant market share and brand appeal to setup N6.
This is what I believe to be Ninty's strategy so longetivity I guess is Wii's main weakness... which is tied in with this.... but it's only a weakness if we are looking at it purely from a straightforward stance.
