Right, he himself was asked if it was more powerful than PS4 and he answered "I Don't Know" the rumor's value isn't in it's performance, but the other details. "Software Development Kits" should pretty much be assumed at this point, as DQ11 was "announced" for NX, so Square Enix has seen the thing in some capacity and found it capable of running their game. With the polygons example it doesn't mean much but could hint at a high clock speed for the GPU and/or a more efficient API for drawcalls being used.I think the point people are trying to make is that no one actually knows what was meant, and people are trying to interpret and extrapolate something that the original poster didn't even know much about - this is simply inferred from the talk of 'polygons', which no one apart from clueless journalists or financial analysts would talk about in this day and age.
Just because it's a rumour 'for investors' doesn't make it true, in fact I'd argue that makes it even more suspicious, from experience.
It could also be that Nintendo opens less production lines (meaning something like 500k consoles per month, rather then million) because they got burned so badly with Wii U. They ended up with huge inventory and they still haven't sold 'em all (I think Pachter said something about 12-15 million units). I'd bet Wii U lifetime sales will end up within that range if NX lauches next year.
Very possible, I don't really hold the Digitimes article with high regards, so 20 million NX devices might not make sense, though in it's first year combined Wii U and 3DS sold something like 19 million.