If I don't mistake, there are motherboards that allows for multiple CPU's. But I can be mistaking on that. Also, there will be a kaby lake H mobile quad-core coming before ww10'17, I don't know if that would come with a fan or not. I don't know about the power consumption compared to the i7 7Y75 used in the eve V, but on the side of performance, a quad core would open more possibilities. For something like a surface book, there can be a manner to use the keyboard part as an aid for cooling so that the quad core can run adequate enough. If I look at surface pro 4, they use a liquid cooling aid aside of the fan, which could improved on I guess, and maybe there could be a manner that the keyboard could aid with cooling for the performance use. If a part of the liquid cooling would transfer heat to the bottom, and the keyboard part would cool the bottom, it could be an improvement.
EDIT: just discovered that the i7 7Y75 is the 7th gen m7 and not a real i7, hence the low power use and the low normal clock speed, so I guess the quad core i7 wouldn't be avaible for passive cooling like the m7 is.