Its an engineering and repairability nightmare, but I've often thought to myself how pretty a phone would be in a seamless soap bar form factor, with an eink display, bone conduction audio, no buttons or ports and just inductive charging.
When powered off it would just be a completely featureless slab. You could even write the devices logo onto the display before powering it off to do branding without redundancy.
https://www.indiegogo.com/projects/light-phone-2-design#