The majority of leakers have said that the number of shaders per WGP is being doubled. It's 30WGPs, 120 CUs, or 7680SPs for a single Navi 31 die, and 60 WGPs, 240 CUs, or 15360SPs for the dual-die module.
That's not how percentages work.
100% is not 40% more than 60%, it's 66% more. The HD 4870 is 40% slower than the HD 5870, which means the HD 5870 is 66% faster than the HD 4870. Scaling isn't perfect of course, but much of the reason is because it's limited by memory bandwidth. If the HD 5870 had twice as much bandwidth than the HD 4870 rather than only 30% more, it would be closer to 80-90% faster. Navi 31 might have a similar issue to an extent, but the much larger infinity cache can make up for at least part of the bandwidth deficit, and Samsung's got new 24Gbps GDDR6 chips (50% faster than on the 6900 XT) .
Because AMD is doing the exact same thing again. The top dual-die Navi 31 card will be several tiers higher than the RX 6900 XT, just as the RX 6900 XT was several tiers higher than the RX 5700 XT.
I'll eat a virtual shoe if it isn't. AMD would have to be very stingy with their product segmentation for that to happen, for example using a single Navi 32 die or a heavily cut-down Navi 31.
And if the top RDNA 3 card (which might be called "RX 7950 XT", "RX 7900 X2", or possibly a completely new name similar to Nvidia's Titan series) isn't >50% faster than the 6900 XT, I'll eat a literal shoe. I expect it to be well over 100% faster, though 150% faster is debatable.
Honestly, I don't understand you guys. AMD is going to approximately double the die area (by using two dies of approximately the same size as Navi 21) while shrinking to N5. How is it not going to double performance? Why is this even a question? The top RDNA3 card is likely to have an MSRP of $2500, possibly even higher, but even if you're talking about performance at the same price point, 50% better is not unrealistic at all.