Here is the problem. Given everything of Nintendo's history, what is more likely:
1. Nintendo uses a 2 year old, released CPU/GPU system that has already got an Android port and sufficient yields to pump out millions of units in a few months (Tegra X1, Maxwell based). The X1 is also basically unused by anyone in the industry (only NVidia Shield) and will probably be super cheap to aquire.
2. Nintendo is going to use an unreleased, un taped out, never used by anyone else, new system (Tegra X2) that no one has any experience with, for a system that is supposed to release in 6-8 months. X2 is based on Pascal but has not even started final manufacturing processes.
Its really, really, really hard to believe any rumors that suggest #2 is true. Yeah, sure, maybe NVIdia has had a secret project to make an X2 based on Pascal specifically for Nintendo and its been a super tight secret. In an industry where every GPU tweak and leak occurs months in advance.