It's gonna house a rocket engine and perform a SpaceX style landing if you drop it. US iPhones are now drop proof (except you need to refill the rocket engine after every fall).Personal flotation device. Cupholder for small, square cups. Tape measure. Emergency sewing kit. Mylar rescue blanket. OLED screen on the back so the selfie-obsessed can use the better cameras. Tiny jumper cables. Itty bitty air fryer (caution, may negatively impact battery life). A water feature. Bento box (the spacer already looks like one). Hand sanitizer. Bear spray.
The list of possible ways to use this space is nearly endless. Come ON, Apple engineers! Show us some real innovation!