Optics is not going to be "solved" by anything but some fascinating kind of metamaterial.

Taking a peek at the research: “While flat-optics cameras have transitioned from theoretical concepts to high-fidelity laboratory prototypes, significant interdisciplinary R&D—spanning nanofabrication, materials science, computational imaging, and systems integration—is required to realize commercial flat camera modules for next-generation smartphones.

Recent breakthroughs have produced multilayer metalenses only ~0.5 mm thick that can focus unpolarized broadband light across several discrete wavelengths.

Dual-Pixel Coded Aperture (CADS): End-to-end learned amplitude masks on dual-pixel sensors have shown >1.5 dB PSNR gains in all-in-focus images and 5–6% depth accuracy improvements in DSLR, endoscope, and dermoscope prototypes.

Color-Coded Aperture Imaging: Single-lens, single-frame depth sensing via color-coded apertures has been demonstrated on DSLR and preliminary smartphone modules with depth map extraction sufficient for basic AR and portrait modes.”

iPhone 4S has camera without bump and makes perfect photos. I don't understand why they are doing that ugly design.

GRIN and micromachined Fresnel lenses are both flat. I wouldn’t be surprised if apple is working at least on the latter

In the far future the camera will dictate the physical dimensions of the device and the display will be entirely virtual.

https://en.wikipedia.org/wiki/Dot_and_Bubble