With over 90 M sold i think we can assume the Wii is a success. But the difference right know is The Wii is now over six year sold ( or older) plus the successor of the Wii released this holiday. So its only normal that Wii sales stagnate. And without any significant software it will slowly die or will sell small portions weekly for maybe 2 years now.
The PS Vita on the other side has many titles releasing this year and is new on the market. So it depends how much it will sell this holiday before we can assume it die.











