There is different percieved value for home console than for a handheld.
It could easily get away with 350, the tablet controller will be novel in a console, and if it has a high selling piece of nintendo software at launch it won't have problems. It's about games far more than price. 3DS struggled with lack of software early on more than with price. Had it launched with Mariokart or ML7 it would have sold fine for quite a while at 250. Nintendo recognizes this problem, as well as pricing, to an extent, but 250 is by no means the limit for early adopters in a next gen home console.
The other consoles lack nintendo's greatest asset, it's own games, which is enough to sell millions of the console by themselves. It will be fine if it gets all relevant 3rd party ports, has the big nintendo games and is around the rumoured power, which is noticably more powerful than last gen.