Iwata thought the Wii U was going to sell
5.5 million units in it's launch year. It only sold 3.45 million.
Then Iwata said that Wii U's second year was going to be the one where the booster rockets were
really going to kick in, and predicted that it would sell 9 million in it's second year, for 12.45 million total. Sales were low all year, but right before Nov/Dec (Nintendo's best selling period), Iwata reiterated that everything was going smoothly. The Wii U stalled out over the holiday and ended up selling 2.72 million in it's second year (6.17 total), which was worse than even it's underperforming launch year.
Iwata shut down production and put out the fire, but production doesn't start and stop on a dime, these things take time to get up to speed and you've made all sorts of contracts with suppliers. Since Wii U crashed into Holiday 2013 anticipating 12.45 million in sales, it stands to reason that Nintendo bought 12 million units or more worth of various parts before it had to shut down. That's why people think Nintendo is sitting on enough parts to make 12-15 million Wii U's.
Nintendo took a big loss in 2013 because they had to pay for those unused parts, but since then they've been able to go back to
assembling Wii U units and calling that profitable.
The Wii U was unprofitable before it crashed. It started out as Nintendo's least profitable system by far, and it's bad first year forced Nintendo to make a price drop they didn't want. The Wii U apparently blows a lot of money on the GamePad and overall the system wasn't designed to quickly drop in price like the GameCube was. It was designed to... I dunno. Even Nintendo's first party studios never asked for the GamePad. Such a senseless design.
Anyways, Nintendo toughed it out, and kept throwing great games at the system, one after another, even announcing more games than they originally signed up for (when they could've been spending that effort on the 3DS), and now they seem to have one or two years of life left in the Wii U, and they seem to be one or two years away from selling 12-15 million consoles at near-full price.
If Nintendo drops the price of the Wii U to try and sell more units faster, they're going to lose their profit margin, and once they run out of spare parts, they're going to have to find new suppliers who can make compatible parts, which probably means a "slim" redesign, but they're going to have to put money on the table again, probably push Wii U back into a money-losing position, and bet that the Wii U has more life left in it. Which is crazy, because Nintendo has almost gotten most of their money back from the last time they bet money on Wii U, and if the price cut and slim redesign don't work, Zelda won't be able to pull Nintendo's butt out of the fire. Zelda has it's work cut out for it as-is. And if Zelda fails,
that's when they fall back on the price drop.
The new narrative for Wii U's success is how much fun it is and how many great games it had on it. It's never going to reach GameCube's numbers, so it's pointless to get worked up about how close it can get to them.