The answer is two fold. Number one is the price of trucks are escalating beyond the middle class ability to afford them. You are only going to be able to go for extended loan terms for a certain term of time-before it doesn't make sense even for the average person. Next is the price of fuel-for those who are able to afford them-only a certain percentage will be willing to pay "European type prices" for fuel if it comes to that.If we go back to my addict example, let's say we (the West) have become addicted to an expensive and powerful domestically-produced painkiller (trucks) for treating everything from headaches to general aches and pains (everything motive related) as a result of the system (doctors) prescribing it for everything, and regulation encouraging this. The solution isn't to say "screw it", scrap the regulation and allow flooding of the market with Chinese Fentanyl for pennies, handing them a dangerous and potentially fatal monopoly. It should be to change the regulation and the system so that this isn't the result while still keeping the Fentanyl out. (Crap analogy but I think you get the gist).
Europe doesn't have the truck presence situation that we have in Canada and the US (I expect there will naturally be disagreement on whether this is a problem or not). This is as a result of them having more expensive fuel and considerably different regulation than we have in North America. As you noted, their domestic marques have successfully sold smaller cars (particularly diesels) in the European market forever, and competitively.
I guess the bigger question is: How does a society whose existence is now predicated on massive and perpetual consumption, break that addiction and shift to something more sustainable, without invoking total systematic collapse?
So-those are two factors (among others-I haven't mentioned) which will have bearing on America's "Truck issues".
I think the long term outlook is bleak for Americas largest truck manufacturer. Their market is a house of cards and it will be awhile-but it will crash down.