I don't think most of you get what he's saying and has been saying all along. It's not a successor in that it cannot be viewed as a clear iteration of either Wii U or 3DS in the way you can clearly view Wii U as a true successor to the Wii and the 3DS as a true successor to DS.
It does not mean it won't replace Wii U and 3DS, but in theory you could imagine it as such, because it's so different from them and has a different concept and appeal. Thus, from a pure concept perspective, it does not make their existing products obsolete in the way they imagine the Wii U making the Wii obsolete. In practice it will of course replace them, and I don't think he has denied as such considering that he knows it will have a big effect on their console sales, but at the same time he wants to feed the perspective that it's not because of the NX's design that they will eventually be replaced, but because they will have played out their role on the market.