I'm sure it will be fine in Japan, but in Western markets, I do think it is going to struggle, which is a shame for Nintendo.
I could buy one right now, but I just have no desire to. However I'd probably pick up a new Xbox when released in a flash. Perhaps further down the line with some good 1st party games I might buy a Wii-U, but for now, I'm just not seeing me making the purchase and I'm sure there are many who feel the same.
The new gamer from a wide range of generations that made the original Wii a success have had their fun and they aren't going to be able to recapture that.