A feature they could still possibly have snuck in would be the ability to cast a feed from the handheld to a TV.

TBH other then a few neat local multiplayer stuff in NintendoLand, there really wasn't much that actually utilized the dual screen in a way that actually enhanced the game. You couldn't quickly swap between the screens like you could on the DS, because the screens were different distances away and required re-focusing your eyes. This meant that most gamepad usages played the same as if you just pressed a button to bring up your inventory or switch views or whatever.

And that's before you take into account the fact that the biggest titles on the Wii U (Mario Kart and Smash Bros) didn't use the second screen at all. The second screen was a gimmick, and a gimmick that was exhausted pretty quickly.

I really loved some of the multiplayer games on Wii U that took advantage of the gamepad. Completely brilliant to have one "special" player with the gamepad + second screen vs. the rest of the plebs with Wiimotes.

I’m fairly certain I remember them suggesting that the original switch was capable of doing this but then they either never granted access to it in the dev kit or they just never had it end up getting used in any noteworthy games.

Nintendoland for the Wii U was _very_ fun in my memory. It was the only title that I remember leveraging the asymmetry of information that different players can have for local multiplayer.

That would be an interesting use of the USB connector at the top --- plug into the Dock and use the Switch as a gamepad à la the Wii U while playing on the TV.