I'm sure we will still run Diesel engines in 20 years. Conventionals will still running the road, maybe more of them with very intelligent drivetrains, but I give it still 5 to 10 years until the autoshifts work well enough that a O/O trusts them.
I grow up in europe and they tried to move most of the freight (and also people) on trains with the result that for example the 7 million swiss people pay about 4 billion $ a year in taxes to keep the trains running (and the tickets to board a train are also not cheap)
A truck is still and will be for a long time the best transportation for short and medium long distances ... and for time critical freight they are still doing well coast to coast.
then RV, I'm sure we are currently just in the beginning of the conversion revolution. Here in the southwest there are not too many conversions. In the Sandrail industry, like Glamis, most customers get fifth wheel toyhaulers, 30 to 46 foot long and 15000 to well over 20000 lbs and they tow it still with 250/2500 socalled HD's. they will smarten up soon. You see also a lot of DP's, but most in sand/desert riding are "younger" couples with kids camping somewhere without a hookup and 99% of the DP's are build for the older couples without kits staying in a campground with full hook up. Also it is difficult to find a DP that can haul legaly a carhauler, most have to small engines (pull and brake) to be considered a TV . And a DP is a guzzler, my Pete is econobox compared to them pigs
That's why I'm sure you will see in ten years a lot more motorhomes based on class 7/8 trucks.
