Outside of things like a Switch Mini and a better dock (I barely dock mine out of fear of scratching) maybe a bigger battery life and the voice chat already included in the console. Though, to be fair, I'd rather have that function included in a revision of the Pro Controller.

-revise the dock to have a cushioned slot that wont scratch the screen

-a better kickstand. the kickstand on the current Switch is terrible. aside from it being flimsy in general, ive found that in a lot of cases, it cant even properly prop up the console.

-make the screen just a bit bigger

Costing more than 150 and having less than 128gb of storage is a deal breaker for me, so if those two are "fixed" I can consider it.

It's more than powerful enough for me, so I'd say a smaller form factor. Something pocket-able, and maybe clamshell.

You'd probably have to give up the joycon, which might be a deal breaker for Nintendo. I could live with it though. I've played two-player games portably about 4 times since getting the Switch at launch. I'd give that up if it made getting on a plane easier. And you could still technically do two player. would just have to bring joycon with you.

I wouldn't compromise for a more portable version if it meant giving up the ability to dock though.

How is life in fantasy land?

Is anyone going to explain how a mini Switch would work? That's all everyone talks about but it's never been explained how it will work. The joycons on Switch are small enough already. The only way I can see a smaller switch is if the bezel is removed(I think that's what it's called?). I guess that would be much smaller but small enough to work as a mini more portable device? Who knows.

An OLED display.

No joycons. (They can pair, but cannot snap on). Controller is built into the system. 

Like a 3DS except no bottom screen, and the top screen takes up almost the entire casing. Speakers fire out the side or the bottom I guess. No bottom screen gives ample room for a second circle pad.

You'd probably need a new dock. 

FWIW, I think the Switch is plenty portable as is. Portable enough that it has accompanied me on 10 or 12 plane flights so far this year, and into five different foreign countries. It works great on planes. It works great in hotel rooms/airbnbs. That's 90% of my portable use case right there.

But there's still the 10% of times in which the 3DS works better.

The joycons don't have a lot of wasted space on them though, so building the controller into the system wouldn't do much of anything... 

I'm looking at the joycons right now and they can barely hold all of that tech together as is, I don't see how an even smaller controller layout built into the system would work.

Not only that, but you'd be arbitrarily blocking the ability to use the basic dock, and the ability to share controllers. It would work against the Switch's concept.