As stated before in this thread; this is not a confirmation of 1080p.
Pretty much all Wii U games display in 1080p, because the console upscales them. Mario 3D World was claimed to be 1080p, only it wasn't. It was 720p upscaled to 1080p by the Wii U. The article linked to in the OP doesn't make any mention of the game being NATIVE 1080p.
I'll believe it when I see a tested confirmation of native 1080p. So far all signs point to it being 720p/60fps (which is excellent, by the way).
Nintendo Network ID: Cheebee 3DS Code: 2320 - 6113 - 9046