I currently own an iPhone 13 Mini which is also considered a niche phone and does not sold well. I guess, I am the wrong person to ask which type of phone should be build. Having said that, I would love if Apple would create a phone with a physical keyboard.
True, at least for horis; though on a vertically-shaped handheld it might make some sense. A traditional slab with a tray-table compatible pogo-attachable keyboard (with wireless option built-in) would be optimal, e. g. a modern version of the piano from the Sharp PC-3000/-3100 or the Psion Series 5.
And ffs, please do include at least a TAB key!
But you're probably more on the mark as the average smartphone user is quite far removed from my feature essentials; I'd prefer even a vertical handheld with a well-designed integrated keyboard to a typical hori without any options.