There is also some debate as to whether or not the overhead in terms of developer time is actually worth it. Real-time raytracing is cool, but it fundamentally doesn't allow us to do anything we weren't already doing to some extent - the most visible impact would be for very minor effects that you would not notice except in very rare circumstances (an example of this would be treating glowmaps as actual light sources - this is something you would not notice during normal gameplay).
If RT comes in, it would most likely be in the form of some minor effects (like real time ambient occlusion) - and even there, there are solutions available that are easier to integrate and more performant on the kind of hardware most people have.
