The 5090's core increase (30%) is actually underwhelming compared to the 3090->4090 increase (60% more), but the real game changer is the memory improvements, both in size and bandwidth.
https://www.techpowerup.com/gpu-specs/nvidia-gb202.g1072
Maybe there is a RTX 5090 Ti being held in reserve. They could potentially increase the compute on it by 13% and the memory bandwidth on it by 25% versus the 5090.
I wonder if anyone will try to solder 36Gbps GDDR7 chips onto a 5090 and then increase the memory clock manually.