The 6S really is not. The jump from the A9 to the A10 was among the most dramatic both in CPU, and GPU. While the RAM stayed the same from the 6S to the 7, the 7 is a much more capable device today.
sorry what? I think you meant the jump from A8 to A9
A9 and A10 are almost identical save for the higher frequencies and additional low power cores. The actual chip itself in terms of the silicon between the A9 and high power A10 cores is *very very* similar right down to the pipelines, cache, everything.
Gpu in the A10 is only a half step up and not a next gen version of the GPU in the A9. Even the A8, which was itself a small upgrade over the A7, used a
generational gpu over the A7
The low power cores do not function at the same time as the high power cores (heterogenous design, mean either the low or high power cores function for a given task) and the A10 is the only modern Apple chip that does this, and the only big.LITTLE design from that era in a major smartphone or tablet that does this
The A9 was a big improvement from the prior 64 bit design shared by the A7 and A8 as Apple completely redesigned or enhanced many components of the cpu in the A9, which was carried on into the A10.
The A10 is like a souped up A9, not as big of a leap as you think it was. Yes Apple has incredible marketing that makes people think processor leaps are bigger or smaller than they actually can be, but the A9 and A10 are very similar. It’s basically the same CPU at a higher frequency
unless Apple decides to stop supporting A9 devices, in theory the A9 devices should be able to run anything an A10 device can. The differences in architecture simply are not there where it would be impossible.
if the A9 devices do not support iOS 15 but the A10 devices do, then there is a bigger business and resource decision behind that than a processing power decision
