A 3nm wafer costs around more than double of a 7nm one. Unless UDNA has some huge increases in perf/w in raster, I think that they will try to get to around 2x of a base PS5 or 60% more than a PS5 Pro, in other words something like a 4070 super (we are isolating raster perf here to be clear).Delivering 4080 perf will be non-negotiable if the end game is path tracing even if budgeting for it potentially does eat into their demographic growth ...
I think most of the improvements here will come from arch improvements, higher frequency and memory bandwidth, and not by making a chip that's bigger than a PS5. So still 56CU's.