Not only is the time when games can achieve good enough results with a path tracer with the kinds of assets they use far off, but also, by the time they get there, there will still be better things to use their rendering time on. There's still a lot of room for improvement with SS techniches, and voxel/point-cloud/distance-field tech is gonna get more and more use.
My prediction is that high end engines from years in the future ( possibly in a next gen ) will use voxel cone tracing or something like that for large scale GI, and they'll stick with screen-space to refine that with high frequency detail. Not unlike QB's aproach. With some 2 extra layers of depth information ( say nearest back facing surface, and sencond-nearest front facing ) most artifacts would be gone, and the remaining ones would be pretty perceptually hard to notice. With screen space reflections getting popular, more games will jump into rendering a low-res-lower-lod dynamic cubemap around the camare ( like many racing and open world games do ) to further avoid frustrum related artifacts - The frostbite team talked about that at siggraph. I think that's be the best use of limited resources, and would look pretty darn good. Of course, completely new aproaches might get developed in the meanwhile.