You can indeed chew through the battery in about 2.5 hours at high load: http://www.anandtech.com/show/9686/the-apple-iphone-6s-and-i.... And the iPhone can't actually sustain maximum performance (and thus maximum power consumption) because of thermal limits: http://arstechnica.com/apple/2015/09/a-3d-touch-above-the-ip.... On the 6s, the CPU clockspeed drops from about 1.8 GHz to 1.4 GHz after 30 minutes of sustained load.

To the extent you're comparing A10 power usage to Intel's published numbers, keep in mind that Intel's TDP is what the processor uses to operate at the rated clock speed at full load indefinitely. In typical usage (where the CPU operates in short bursts and sleeps the rest of the time), the average power consumption will be a lot lower.

7 / 2.5 is still under 3w for the total prone draw.

All of which suggests in a laptop with active cooling and higher energy budget say 20W you could sustain 2+ ghz x6 cores or 20,000 to 24,000 with minor adjustments. Which is in the ballpark of Intel's high end desktop performance and faster than their mobile chips.

The real issue is Intel is dealing with a well funded competitor who does not care about x86. And the computer history has a long line of companies who where eaten from below as people where happy to pay a lot less for fewer features.