As the guy says in the article it's likely for their next handheld. We should be due for the 3DS successor around 2017 or so meaning development would need to be underway.

Of course they have begun to develop their next console, handheld or not. Most probably handheld since they always launch that one a year or two before their home counterpart. Or maybe a hybrid like some rumors say. It takes years of research and development.

EDIT: What is SoC if I might ask?

I'm guessing System on a Chip, what Nintendo usually uses for backwards compatiblity.

I think people might be reading into this a little TOO much. Every hardware company is ALWAYS doing R&D on their next products ahead of the curve, this is just the way it is. It almost feels like people are pointing this out with Nintendo in an attempt to do an implied "Nintendo is doomed, they're already working on new hardware because the Wii U sucks" kind of spin...

Couldn't this just be Nintendo doing another sku of either Wii U or 3DS? Maybe they're just finding cheaper parts for their current consoles.

If it was up to me, I would of not began the development of the Wii U after the Wii, instead focus on working on a handheld that work similar to the PS Vita TV, sobit will be powerful enough to have console like graphics, but also have that portability to.