The PS3 and Xbox 360 sold at a loss for like 5 years at least. The Wii U has been out for 8 months. This isn't really a big deal, and certainly not worthy of the "Nintendo is doomed" and "the Wii U is dead" comments.
Anyone suggesting they go software only or that they kill the Wii U and put out another system already are kidding themselves. Both moves would be stupid.
The difference being between Microsoft and Sony, and Nintendo is that both Microsoft and Sony have other businesses that can see them through losses for their respective systems for the short term. Nintendo, on the other hand, sole business model is video games. Them selling the Wii U at a loss will have a bigger impact on the company and I don't expect that they will continue in this regard.
I would not like to see Nintendo go software only, but it is reasonable to expect that they will come out with something that is more powerful and flexible than what the Wii U is. I think those kidding themselves are Nintendo fans who think that Nintendo can do no wrong.