Just mirroring the general opinion on anandtech forums that the current iteration of 4060 which is based on AD106 should really be a RTX 4050 and the RTX 4080 should use AD102 and AD103 should be an used for the RTX 4070. The basis of these arguments as you have kind of shown is based on the die size and the memory bus.
Maybe these people are perhaps exaggerating, to perhaps increase the disdain that Nvidia is ripping them off but if Nvidia was aggressive or AMD was more competitive, we could see these larger die sizes be used.
I think a fully enabled AD102 has more in the tank because if we look at how much the chip is disabled, its quite a bit more than the RTX 3090 to 3090 ti which which had a 12% difference in performance. This most important part however is considering how much l2 cache was cut. The RTX 4090 only has 72 out of 96MB of L2 cache, considering how much more performance AD102 has than GA102 but with largely the same bandwidth, this is likely quite the bottleneck. GA106 has 32mb of L2 cache, something with as much power as AD102 needs more than a measly 72mb.
Also with the current design parameters of Navi 3x series, I think what your more likely to see is a jump in specs akin to Navi 32 to Navi 31 for 400mm2 of add die. Basically a 33% increase in specs vs current Navi 31. What your suggesting is something asymmetrical to the current design of the Navi 3 series making the engineering even more difficult. Also packing it too tightly would limit clocks and just increase the problems AMD already has. You would also need to a couple more MCD making this a monstrous 700mm die and if AMD current problems with Navi 31 regarding clocks and power still existed(likely magnified with a larger die), you would likely just get something equal to the current RTX 4090 maybe even lose, while Nvidia releases a fully enabled AD102.