Cool picture, but A6 is just a marketing name, even if true we still don't know much about what the CPU will actually be, other than it won't be identical to the A5/A5X.
It could be, in order of likeliness:
1) Dual 32nm Cortex A9s clocked higher than in the A5.
2) Quad 32nm Cortex A9s.
3) Dual 45nm Cortex A9s clocked higher than in the A5.
4) New core architecture (A15s in advance?).
The first is the most likely because it would give a performance boost without affecting battery life. You could even get better battery life than with the A5, depending on what clock they give it. They also already have experience in producing 32nm SoCs with the (post-new iPad) iPad 2 and the 1080p Apple TV, which means they could have high yields with a low defect rate.
Given that the leaked battery only has a marginally higher capacity than the 4S's, it would seem unlikely that the CPU would draw more than the A5 given that the bigger screen and LTE chip would also draw more, resulting in a decrease of battery life which Apple would try to avoid. That's why I don't think they will throw in 4 cores or overclock the current 45nm cores.
The last one is not likely at all because even if Cortex A15 cores were ready to be produced right now, I doubt they would be in the kind of yield Apple needs with a product as successful as the iPhone.
I think Anantech's analysis is right, and it wouldn't be surprising to see a new marketing name (A6) even if neither the core architecture or number of cores have changed. After all, that's exactly what happened between the iPhone 3GS and iPhone 4 and they changed their marketing approach by naming the iPhone 4's SoC A4 while not giving a name to the 3GS's SoC.
We should expect a performance difference similar to the one between the iPhone 3GS (single core 65nm Cortex A8) and iPhone 4 (single core 45nm Cortex A8, clocked higher, double the RAM).
iPhone 3GS (left) vs iPhone 4 (right)
For reference, the switch to a 32nm SoC in the new iPad 2 gave a ~25% battery life increase. Given that the iPad's screen draws more energy than the iPhone's proportionally to the rest of the components, the SoC's efficiency is a bit more important in the iPhone than in the iPad, and we could expect maybe a 35% battery life increase by switching to 32nm A9 cores in the next iPhone, at the same clocks. If we cancel this energy saving by overclocking by around 35%, we would get roughly the Integer/Floating point performance gains shown in the above iPhone 3GS/4 comparison.