You make many good points, but I still feel like you're really underselling the potential of simple ray tracing. Hardware acceleration of intersection testing and BVH construction/traversal is only going to become more prevalent, and with temporal reprojection and spatial denoising methods, many kinds of noise can be mitigated. It doesn't even have to be that complex -- "An Efficient Denoising Algorithm for Global Illumination" by Mara et al. is only 7 pages (more like 5, really).

Regarding spectral path tracing and colored noise, Wilkie et al. have written a good paper on this, "Hero Wavelength Spectral Sampling", if you're interested.