What could the Switch2 'Gimmick' be?

[Wman1996]

JackHandy said:

I don't think there will be one. I think it'll be like the SNES, which was basically a much more powerful NES with a few more buttons. Could be wrong, though, but that's my guess.

That would be great, but I'm skeptical. I'm pretty sure the GBA (whether you include the GBC in the transition or not) was the last time a Nintendo platform transitioned to the next without gimmicks. I suppose you could say the N64 and GCN fit the bill, but arguably their build/appearance and game media are quite gimmicky. N64 had cartridges still when they were expensive and tougher to pirate, and GameCube used miniDVDs because they were less practical to pirate than CDs and DVDs. Even on the controls side, N64 had four of its face buttons as a camera control gimmick instead of having 4 normal face buttons and two sticks. N64 stubbornly had a three-pronged controller with a weird button layout its whole life instead of making something similar to the Dual Analog and DualShock. 

The most ideal situation would be as you said iterative with no new gimmicks out of the box. But Nintendo is probably going to add something gimmicky even if it doesn't get in the way of the experience (like Switch had HD Rumble and an IR sensor).