"A rising tide lifts all boats."
Your theory is assumes other iPhone models won't get SiC. And there is a satiable amount of battery life consumers want. After that, they will be satisfied. But that's not how it works.
People are not buying iPhone Air because it compares poorly against other models in the lineup, not because they think 27h is too low.
After SiC, the difference in battery life across all models will still be the same. A second camera will still reduce battery life, making the gap larger. The question still remains: why pay $999 for less battery life?
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