foldy iphone would be cool but i don't know i guess i'm just not creative enough to envision myself in scenarios where i want a bigger screen during my handset time anymore. if there was some sort of apple pencil as part of it that came with it, that actually changes the calculus just a smidge cause i enjoy doodling. i guess note taking "on the go" might mean something to some, but i supremely doubt apple is even remotely interested in bringing their pencil experience to the iphone.
It makes the screen bigger, which is great for photograph viewing at a further distance from the device, and generally larger amounts of text on screen, at the cost of a 30% heavier and more delicate device.
My eyes are 52 and they appreciate the larger characters, often times.