Maybe there will be no design changes, Apple will go with same back panel, square-shaped design, and same camera module placement. But the module will likely be more prominent.
Every year Apple may or may not upgrade something but it definitely upgrade the camera. And some rumors are claiming that iPhone 15 Series will shoot upto 8K Video.
Another big upgrade you can see in camera is Periscope Lens. And this will help to capture great portraits with background blur and sharper foreground.