OHV NA motor is more efficient in Highway, and some driving scenarios. But Ford builds vehicles to meet the EPA fuel mileage test specifications...and the ecoboost technology is made to get the best fuel mileage under the blanket of EPA testing that is done vs a NA motor.
GM has been anti boosted motors in trucks too...they have a small motor (going to shock everyone) going into the new Silverado/Sierra.
FCA is doing the same thing with there 2.0l turbo. the Big 3 are trying to replace V8s with V6s, and V6s are being replaced with I4 turbo setups. Ford doesnt offer a V6 any longer in the Fusion only 3 I4s.
The 2009-10 F150 had 3 V8 options
The 2011-14 F150 Had 2 V8s options 2 V6 options
The 2015-19 F150 Has 1 V8 option 3 V6 options
There seems to be a trend here.
The 2007-13 Silverados had 3 V8 options
The 2014-18 Silverados Have 2 V8 options and a V6 option
The 18.5 Silverado will be a surprise
Obviously, it would be hard to argue that there isn't such a trend both in the specific examples you cited and across the industry. I do appreciate that you acknowledged the EPA testing is less than realistic. I had hoped that when VW got in trouble it would cause a shake up in the testing methodologies that would require more realistic testing.
I also personally would love to see an undersquare 4.0 liter V8 EB engine. In an eco mode that would bleed off boost, you'd still have plenty of grunt and would be getting some pretty solid fuel economy. Truck could be driven like that in most scenarios. And then under full boost, it would be a monster.
Anyway, the V8 ain't dead yet. Long may she live.