AFAIK current state-of-the-art in pathtracing are still metropolis light transport methods. Seems like current research is mostly focussed on denoising - which makes sense, since a good denoising provides a valuable shortcut for quicker results.

While I only occasionally glance at new results in this area it seems that CNN-based denoising techniques look quite promising, possibly getting us close to viable real-time pathtracing at least for "suitable" scenes. I am more confident than ever that a shift to traced renderers could be next - this has nothing to do with RTX and the buzz around it though...