Yes it's very clear even with this not being an official translation. The NX is not the successor to Wii U or 3DS in terms of design or branding, hence the following sentence, it's a new way to play. It isn't a Wii U 2 or 4DS, but that doesn't mean it wont replace them. The keyword in the second bold is "pure." Just like when Iwata said "simply," that means it isn't just a straight up replacement as we've come to expect but more than that, aka replacing both 3DS and (not or) Wii U. The fact that they mention both Wii U and 3DS makes that much obvious.
Also I left it out of my original post for fear of being too mean, but in addition to reading comprehension is common sense. No way would Nintendo entertain the possibility of supporting three systems at once when they can't even do two, especially when it would contradict what they've said about merging their handheld and console software output.
LOL really? Nintendo HAVE entertained this in the past, so they have set a precedent which trumps "common sense".
"[It] will enable fun and movement not seen before. I expect it to become a third pillar, next to GameCube and Game Boy."
-Satoru Iwata, Gamasutra (January 07, 2004)
You stated Nintendo never said the NX won't be a replacement to the Wii U, I showed you they did actually say it and then you went into semantics and ambiguity of the word "pure". Well damn, I guess the Wii was not a 'pure' replacement for the Gamecube because it had motion controls and was a 'new way to play'. Much like the N64 had an analog stick compared to the SNES's D-pad. You even mention difference design and branding being factors in a console/handheld not being a replacement. Well I guess the Xbox One is not a replacement to the Xbox 360, well I guess the Gamecube was not a replacement for the N64, or the Genesis to the Master System, or the Vita to the PSP...
I also don't want to sound mean, you sound pretty cool to me, but I do think the explanation is quite evident.