Comment by bob1029
It will never be fast enough to work in real time without compromising some aspect of the player's experience.
Ray tracing is solving the light transport problem in the hardest way possible. Each additional bounce adds exponentially more computational complexity. The control flows are also very branchy when you start getting into the wild indirect lighting scenarios. GPUs prefer straight SIMD flows, not wild, hierarchical rabbit hole exploration. Disney still uses CPU based render farms. There's no way you are reasonably emulating that experience in <16ms.
The closest thing we have to functional ray tracing for gaming is light mapping. This is effectively just ray tracing done ahead of time, but the advantage is you can bake for hours to get insanely accurate light maps and then push 200+ fps on moderate hardware. It's almost like you are cheating the universe when this is done well.
The human brain has a built in TAA solution that excels as frame latencies drop into single digit milliseconds.
The problem is the demand for dynamic content in AAA games. Large exterior and interior worlds with dynamic lights, day and night cycle, glass and translucent objects, mirrors, water, fog and smoke. Everything should be interactable and destructable. And everything should be easy to setup by artists.
I would say, the closest we can get are workarounds like radiance cascades. But everything else than raytracing is just an ugly workaround which falls apart in dynamic scenarios. And don't forget that baking times and storing those results, leading to massive game sizes, are a huge negative.
Funnily enough raytracing is also just an approximation to the real world, but at least artists and devs can expect it to work everywhere without hacks (in theory).