Optical interconnect in the rack is a thing already. It's just a matter of time until it moves to single-PCB scale. And most persistent memories (competing with DDR memory for speed, and with far lower wearout than NAND) are of the "3D storage" type.
Maybe now we will start to see the "optical" CPUs start to be a thing. Or the 3D disk storage,;or other ground breaking technology.