One great and unique feature for your upcoming phones would be to integrate the phone protection in the phone itself.
I mean, that’s so ugly using a case (even transparent) with your beautifully designed phones. I guess +75% of users are actually using cases for their phones, hiding the essence of the nothing phones. (so do I…)
Don’t you want people to showcase how beautiful you phone is ? 
You would be the 1st company to do that 
I think this may be possible with multiple implementations (using replaceable parts):
- corners only bumpers
- all round bumper shield
- using the system from the CMF phone but using a transparent back (glass or plastic)
(PS if, in addition, you check the hot swap battery option, you would be golden 
)