I'd like to see more energy-dense batteries, not lithium ones really, but something such as the theoretical lithium-air ones with energy-density comparable with gasoline. An energy cell that allow us to charge once and it'll last for days, preferable one that recharges very quickly to(within a minute, or two for example).

A button wouldn't hurt anyone, button is nice, button is great, feels so good to press one when I want to minimize my app, and go back to my "desktop". Current Smartphones are weird imo.

Removable batteries, that'd surely be amazing at least for someone who plans to make a phone lasts for several years, when it is dying out just remove it and replace it, plain and simple.

Chips with smart architecture, so it can process more information more quickly.

Also foldable smartphones everywhere, becoming as ubiquitous as our regular smartphones, tho seems unlikely in a third world country such as mines.