In the original Lovelace leaks, the AD102 was going to include 144 SMs. And while I think we discovered that's technically true for a die with zero execution units fused off, the actual shipping AD102 product only exposes 128SMs. Thus, with 128 CUDA cores per SM, that provides the 16,384 total CUDA cores of the consumer RTX 4090.
This said, I wonder if the rumored 192SMs on GB202 is the total units on a 100% functional die, or the expected usable units on a production-release die... 192SMs would deliver a 50% increase over the direct predecessor, for 24,576 CUDA cores. This is roughly in line, albeit a little short, of the jump in core counts from the 3090 to the 4090...