I would say that in the relatively small realm of Rving, yes the more capable pickups have largely made MDTs obsolete. A buddy of mine had a mid-2000s F650 to tow his 40' fifth wheel and he says his new F350 6.7 is superior all the way around for towing his trailer. But the real world of medium duty trucks is doing work that pickups simply can't do no matter how much power and torque they have- hauling a 24' van body full of freight, a dump box with 5 yards of gravel or a flatbed with six or eight pallets of concrete block.
