Floating gestures might have more success with Theremin-esque[0] audio feedback. Imagine an interface that hums when you put your hand near it, and also makes other interaction noises as you use it.
Now imagine a train or a plane packed full of people using Theremin-esque humming devices.
We're basically out of technology for the next innovation period. The truly "magical" next step is a direct neural interface, and we're an unknown number of years away from that.
Nothing else can improve on the hand-sized touch screen. The alternatives all come with serious compromises. Voice is too loud and public, portable floating holographic displays haven't been invented yet and may suffer from privacy issues, and there's not much else available.
In-eye projection is probably the most promising approach, but the product would have to be no heavier than existing glasses, and I can't imagine that being viable for five years at a minimum. A decade would be more realistic.
We might have LCDs with holographic resolution by then, so all kinds of interesting things might be possible. But for now, hand-sized touch screens are as good as it gets - and will be for quite a while.
Of course there's still a lot you can do with a small touch panel. There's huge scope to make software much, much better and smarter than it is today.
Imagine a train full of people with giant paper displays, flapping the paper, hearing crinkle and crumple each time they so much as flip a page! What a racket!
[0] https://en.wikipedia.org/wiki/Theremin