This is all entirely dependant on whether Nintendo has something in store to boost Wii sales, like more bundles for future releases, or if they have software in store that will expand the market once again (eg Wii Relax).
Sales race threads like these are kinda pointless when Nintendo's involved, because they always keep their cards very close to their chest up until the very last moment. We don't know what they have planned for the Wii this year. A lot of people in this thread are going to assume they don't have anything planned for the Wii this year, mostly because they would like to see the Wii lose. But the truth is we're not going to know for sure until Nintendo wants us to know, or the year is almost over.