This image here, taken from a patent filed by Nintendo with the US authorities, appears to confirm the Nintendo NX removable controller rumour we've heard previously, with the paperwork showing a handheld device with, yes, a controller coming away from it.
The patent describes this as being a "portable game machine which may be carried by a user," which is one the the most vague statements possible to make. The drawings are really quite specific for a patent, though, appearing to show just the d-pad element being removed. That's quite an odd way of accommodating multiplayer gaming, with the patent also illustrating a scenario where the d-pad is swapped for an element with... more buttons on it.
It all looks in danger of being an overly complicated and somewhat baffling solution to problems not yet invented, as surely all Nintendo fans really want after years of innovation is something with lots of oomph to empower them with Marios and Zeldas for the next eight years, not this clunk-click swappable hybrid business. [USPTO via Twinfinite]