So I took a long hard look at the trailer again, and noticed a few things.
Firstly, the car holder thing has an assortment of holes in it. One is for the cartridge slot, curiously. Another on top for the vent, and a pair along the bottom of the back, matching the long thin holes on the back of the console I thought to be intakes previously. No holes on the bottom.
Now, following with the assumption that air is a substance that cannot be generated inside the console, it needs to get in there somehow, so the long holes on the back of the console's main body are pretty definitely intakes. Long, spanning most of the width, so hard to totally obstruct.
Then, I caught the briefest of glimpses into the space inside the dock where the console is slotted, it's visible for a split second when the woman towards the end of the trailer takes her Switch out of the dock. It's all tiny and blurry, but there's definitely some kind of protruding contact plate in the middle, no surprise there - and there's something on the back of the slot, towards the bottom. Impossible to make it out without CSI:Miami's "zoom and enhance" technology, but it's something that may or may not be a slot/opening leading into the back of the dock.
And finally there's a brief moment in the esports scene where the back of the dock is visible. The entire top of the back, like maybe 20% of its height, is one giant intake. At first it looked like maybe a shadow from the monitors in front, but it is way too uniform, way too dark, and just way too weird-looking. It's a big, rectangular black hole. There are no other openings that could let air in for the docked console.
So. The dock is increasingly looking like a supercharger station. There is no need for a dock that's "just" an assortment of connection ports and charging circuitry to be that large, and I don't think a giant hole in the back is something that might be needed for something else. Added power and added cooling seems to be its main purpose, so while it won't actually contain any extra processing power, boosting the console's performance should be a thing that it's going to do.