I always believed that the reports of the Wii-U's death on arrival were greatly exaggerated, if only because I think it's quite obvious that a system will have a hard time selling if interesting software isn't there to back it up. The PS3 went through the exact same cycle when it was released with a very over-priced tag, and it turned out to be just fine once the AAA games started pouring in, and Sony realized that the target audience isn't a bunch of millionaires who have chump change to spend on a home console.
I'll be the first to vouch for the Wii-U having a good enough library to justify purchase already, actually. Super Mario Bros reminded me so much of Super Mario World back in the day when I first played the GBA port. Pikmin 3 is my personal favorite in the series, and just the breath of fresh air that comes with that style of gameplay was enough to hook me again pretty quick. I just got Wind Waker HD today too, and I hope to maybe make a thread about my thoughts and impressions if I can keep the original post at a reasonable length. Point is, you'd be a fool to not think that it will only get better from here on out. Plus, the 3DS is on top of the world anyway, so Nintendo can afford to have a sluggish start with the Wii-U.
Those sales numbers a pretty amazing though. I wouldn't exactly call Wind Waker HD THE selling point though. The game isn't all that radically different from the previous Gamecube incarnation to me, because the graphics don't necessarily gain a lot from the HD capabilities. It's probably just a good breaking point for a lot of people who have been considering getting one for a while now. Smash 4 and more Mario World or on the horizon, so if WWHD didn't rope people in, those surely will.