I don't like calling them gimmicks, because the line between "feature" and "gimmick" is mostly marketing. And I'm not sure I'm clever enough to predict anything - I couldn't have predicted the DS, the 3DS, the Wii or the Wii U. I had played a lot of joystick games with arcades and the Atari, and really hated them, but I couldn't have imagined the thumbstick on the N64.
I don't have a hope, exactly, but I think the Wii U had untapped potential, and Nintendo has a huge library of dual screen games from the DS/3DS era. The Switch really felt like an attempt by Nintendo to consolidate its whole history - touchscreens
and motion controls, the GameCube's controller
and the Wiimote + Chuck, a TV console
and a handheld. It was a really elegant design that way - but it left two screens behind.
It would be neat if Nintendo could bridge that gap with something like screen casting ("wireless docking" maybe?). And in 2031, when Nintendo makes it's eventual cheap VR device, we can get 3D effects from 3DS and Virtual Boy games and the snake will have finally eaten it's own tail.
And I'm assuming the device will be called the Switch Up, for no other reason than I like it.