Moore's Law hasn't really fallen off yet, unless you're only looking at serial performance. True, the 10Ghz processors that were promised with Pentium 4 never materialized, but then came dual-core and quad-core CPUs, not to mention the explosion of GPU performance. Path tracing maps well to parallel processing; the main trick these days is keeping all the silicon fully utilized.
The parallel processors, most notably GPUs, have become more power hungry and more expensive at the top end with every generation. In the case of multicore CPUs, the core growth for consumer models has stopped at four cores. The typical workloads in the consumer market do not seem to scale much beyond that.
Server processors continue to gain more cores per die. But some server workloads scale so well that there is now a trend to move to an even higher number of smaller, slower, more energy efficient cores with the same or slightly lower aggregate peak throughput.
Moore's Law by the letter, namely that the number of logic gates will continue to grow (with no mention of any performance metric), will hold for another while. But we're already at the point where you get only one improvement of the three: performance, energy efficiency, cost. We used to get all three improved, or at least two out of three, but that hasn't been the case for a while now.
Additionally, the improvements which we did get recently no longer lie on an exponential curve. Instead we are in a phase of slow linear improvements, which I take to mean that we are near the inflection point of a saturation curve. That would indicate an asymptotical limit of growth in the relatively near future (a lot nearer than the time it took from the first electronic computers to the inflection point, I am guessing).
I am not even sure that realtime 3D graphics is embarrassingly parallel enough, given the development of price and power consumption of the last few generations of high end GPUs.
(Clarification: I am not trying to win an argument here. If what I say is not convincing, then I could simply be wrong. I am trying to give an advance warning to those who are still betting on the Moore's Law of old.)