Great article! Really enjoyed reading it.
The 'Barber Shop' render, taking nearly 10mins on a 2080 to render, is a sobering reminder though of just how far away we are from movie quality CGI in real time at high resolutions for games on PC GPUs. Even if we're only talking about 30fps, never mind 60 or 120.
With all the up-scaling trickery now being developed, We're still going to need RT performance hundreds / thousands of times faster than the current best.
I can't see that happening without serious amounts of extra hardware on the GPUs themselves, Dedicated multiple RT rendering cores like modern CPUs, seems like the only realistic way to do it.
..and that's just to render the current state of the art in movie CGI, which itself is getting ever more complex & realistic each year.