Even if these rumors about NX being clearly more powerful than PS4 are true, everybody should be careful and not expecting (to avoid disappointments):
-Nintendo trying to make games that looks better than PS4 best efforts (Uncharted 4 and the like)
-Nintendo giving its developers (like Retro Studios, MonolithSoft) millions and millions to make graphic intense games that competes with studios like Square-Enix, Bethesda,....
-Third Parties actually trying to make the NX version of a game the "definitive version" (best graphics, physics, ai, etc)
Sure: the jump from Wii U to NX will be massive and Nintendo's games will probably look stunning, but stunning comparatively to Wii U games, not PS4 ones. I can't see Nintendo bleeding money just to please "graphic whores" and squeeze 100% of NX's power. For them, artistic direction comes first.
EDIT: Oh, I forgot: Zelda U won't look that much better on NX even if this rumor is true (same reasons as above). I'd love to, but I just can't find any reasonable argument for it. People expecting Zelda U on NX being a next-gen graphic showcase will end up disappointed, IMO.