Personally, when I view a very-wide display I find the short dimension limiting and want it to be larger in comparison with the larger. I'd prefer something squarer.
I was going to say "good luck pocketing that" when I realised that my wallet is about 4" by 4". Which opens up a whole plethora of possibilities including single panels, clamshells with a single display and a proper keyboard, or twin panel touchscreen displays.
And finally, for idiots everywhere, a concertina of about five panels.