A USB-C Port
I know it’s not a software feature, but hear me out. I think it’s about time we get an iPhone with a USB-C Port, at least in the next iPhone Pro. Other Apple devices already use USB-C, like the iPad Pro and every MacBook, so it would make sense for Apple to make that jump with the next iPhone.
A USB-C port would let the iPhone connect with many other devices, like any Android device with a USB-C port does. So it would need improvements in the iPhone’s file management interface as well.
Sadly, this probably won’t be the case. Apple’s iPhone 12 prototypes are basically done, and Apple has been testing their new AirPower prototype. Apple’s planning ahead for a wireless future, so we might not see USB-C at all.