1) Its still selling at an amazing rate ,
2) No signs of a price drop , hell the price is going up,
3) Its destroying competitors,
4) Nintendo has spent such a long time in a drought that its not even going to attempt a release until its truly threatend,
5) Its making so much money on the sidelines while Sony and Microsoft fight it out,
6) Its trying to identify its real enemy ! Sony or Microsoft,
7) Doesnt want to risk losing its user base.