What big things to work on in computing besides AI and quantum?

A question with a similar title was asked here a few days ago, but they were actually asking for advice on side project ideas. But it got me wondering about the general question.

On the hardware side, I've heard a lot of conflicting predictions about optical computing and optical interconnects, both with a CPU and between the CPU and memory. I'm skeptical about the former. The latter has been 'just around the corner' for years now with no sign of becoming mainstream.

But what else?