I noticed a lot of white trucks too. I bet they never made a blue one for example. 90 % white and 10% black.
A few other things a 2019 truck will have that a 2015 truck does not have. That is LED lights and probably will have daytime running lights. Also will come with Apple Car Play and Android Auto.
My 2017 F-250 has a lighting package that lights up the bed and beyond. I only played around with the Android Auto and so far it seems really cool. I can see letting the free satallite radio run out and using I

radio instead. Also navigation with Google Maps or Waze.
I rented a car that had adaptive cruise control. That was a big thumbs up feature. We have a 2015 car which seems old because it does not have the latest features. Oh sure, it has Lane Keep Assist, Rear Traffic Alert and Blind Spot Detection but that is it. Now our next car will have the automatic braking and adaptive cruise control with Android Auto.
I guess I would value the 2019 truck maybe 20 k more than the 2015. Being 4 years newer alone might be worth 20k. In 2012 I paid 60k for the F-450. I got 40k at trade in with 36,500 miles.. That was 20k depreciation 6 years.