It’s probably part of a long term goal of eventual removal of the notch for something like a truly bezel free display. It will be huge- the first iPhone with Face ID that doesn’t need the notch. They’re looking ahead 5-10+ years and that’s why they’re in no rush to ditch the compromised screen design. It’s like the longer they hold out the more impressive it will look when they finally ditch it. Look how far iPhone has come, it no longer needs a notch after all those years, must have been really hard to figure out a place to put those sensors other than top and center on the screen. I bet when they finally do change it the sensors will just be in a row along a narrow bezel the way they should have done it in the first place.