You may be incorrectly assuming all A7 SoCs are identical. The Apple TV has an A5, but it's only single core, unlike it's dual core phone and tablet brethren. Maybe they just dropped the X moniker.
You could be right, but have a read of the review I linked above, search for the text I quoted, and read around that. To me, it's compelling that the iPhone 5S's GPU is severely underclocked, leaving headroom for reuse in the iPad 5. And of course higher-clocking is usual in iPads, with their larger battery.
BONUS: for next year, the G6630 gives 50% performance increase + the expected node shrink allows a further ~30% overclock. 1.5*1.3 = 1.95 ~ 2.0.
For the following year, they could go for G6630MP2 (the 6 clusters can be multicored as a whole). Next (three years from now), they could go G6630MP3 plus another node shrink. By that time, there could be 8/10 clusters available G6830, G6A30 etc, and an entirely new architecture in the works, though probably not yet available.