Since you don't at all, it will last longer but not that long. I've seen a handful of those engines go 100k but they-re all worn out at 150k. Change the oil every 5k, the trans. fluid every 30k and don't drive like a crazy person if you want it to last some time.

The 3.5 is the only one to think about. I will say the new gen has come a long way from the 1st. Lots of power for sure but it comes at a cost. The only hope for longevity is more frequent maintenance intervals such as oil, sparks, ect. Personally I would change the oil every 3k mi even with full synthetic and spark plugs every 60k mi. 

We all know my thoughts on 2018+ F150's. Not good. But you should get 100k miles out of it if you truly maintain it well.

I'm not a fan of that engine/ vehicle combination. That 2.7L V6 EcoBoost engine would probably have been a great motor to put in a hypothetical Raptor model of the old Ford Ranger, like my 1999, but it doesn't belong in a full size truck. It's too small for that heavy of a vehicle -the displacement is 0.3L less than the 3.0 Vulcan in my Ranger. When my engine was new (it's pushing 270k), it put out 142 horsepower. It was also made for a sedan, not a truck. It shows. That 2.7 probably puts out similar power without that turbo ramming air into it, and it will likely never see that high of mileage in the full size truck. If I remember right, that engine was in the short-lived Fusion Sport. An application not anywhere near a truck. 

In the old Ranger, I think a 2.7L EcoBoost would have gotten great gas mileage and the 325 horsepower and 400 ft pounds of torque would have made for a blast of a compact truck to drive around. Ford could have also put it in the new Midsize Ranger instead of the 2.2L Mustang EcoBoost engine. They seem to be obsessed with gas mileage and not common sense with their truck designs nowadays.