Neither rushed nor delayed: rushing it would mean either making it too underpowered even for Nintendo's prudent standards or having to choose between overpricing it or accepting small profits or even initial losses on HW, and there would also be too little time to build up hype; delaying it too much would mean giving competitors an excessive head start (Ninty knows giving one year to the earliest is proven to be acceptable, but more would be a dangerous gamble).
So 2012-2013, maybe even 2014, if the earliest competitor launches late enough and Wii doesn't drop furtherly too much, but neither 2011 nor 2015. And whatever Ninty decides, I expect it to put Wii again in a good shape before starting the marketing machine for its successor, its brand name and recognition, and its potential profits not reaped yet too, are too precious to be wasted.
