"They've been actively focusing on increasing power efficiency for a number of years now, so I have no doubt they'll be able to bring strong competition."
It Intel wants to, they can bring strong competition. They used to have their own ARM variant, but sold it off. They decided that there was no future in low power. Oops.
When they do get a low power chip they seem to lose interest, and then crank up its performance, and its power budget. Then Steve Jobs would yell at them, and they would produce another low power chip. Then repeat the cycle. Now that Steve is gone, will they go back to thinking a 135W CPU is acceptable?
In Intel's world, Grand Coulee dam exists to power their CPU, and the rest of the hydropower on the Columbia is to run the cooling system for that chip. Institutionally they haven't figured out that we have all the cycles per second we need, and battery life is now the critical parameter. Obviously if your dream PC has a 1000 W power supply on a dedicated circuit you will not care about power the same way you will if your phone keeps going dead every time you need it.
As is often the case, the problem is Management, not Engineering.
For the record, I'm using a 2.5 Ghz Core 2 Duo P8700. It's 6 year old technology and entirely fast enough. It has a 25 W power budget. The "ultra-low power" 2 core Haswell has a 35 w power budget. So they have gone backwards. Remember, I don't need more speed, so I don't care if the Haswell CPU is faster.
The question is does Intel get this point? If they say "you are not our target demographic" then fine, and I'll pay them just as much attention as I pay to Miley Cyrus. Which is to say none.