The f-35 will be the last manned fighter. The ability to loose the pilot is huge for a number of reasons. G-limits, oxygen, egress, and many other design limitations.I could absolutely see trucks being the first legal DVs on the road. They are already a huge investment so fitting them with the required hardware, senors, monitors, etc. would be a smaller percentage of the overall costs.
They also can be run over set routes, and many fleets already have real-time feedback on location, speed, etc. for tracking purposes.
And as you mention, the cost savings would make them very attractive for fleets, especially since without having to worry about drivers, they could be on the road 24x7x365.
However I still think the first real DVs will be on the military side. After all, the whole basis of today's SDVs were the various DARPA Challenges that started off in 2004.
Imagine what a fighter jet could do if it didn't have to worry about how many gees it was subjecting the pilot to. How small, fast and nimble could you make it if you didn't need the double and triple redundancy required to protect your expensive and delicate human inside?
And with all that redundant gear and space out of the way, you can have a much larger ordnance load, and a much lower cost, meaning you can field far more of them. You would still need a human in the loop, but they would be much higher up in the food chain, giving orders rather than trying to steer the plane.
Same logic applies to tanks, ships and any other piece of major military hardware that's currently manned. The first major military that goes to DVs will become one of the most potent militaries in the world almost overnight.
On the subject of Tucker, you're right that the false accusations and outright slander against what was a ground breaking car was what killed it. However that was mostly instigated by the big Detroit manufacturers of the day.
Once GM, Ford, VW and such have good solid EVs to compete with Tesla, we may see a replay of that. To be fair, there's lots of dirt they could spread about Tesla that would be perfectly true. Mostly around their QC and service issues, but if you are Liberal-minded their 'unfair labor practices' (aka making people work hard) come to mind.
If you look at the early history of the car, almost none of the companies that were so revolutionary at the time even exist today as brands, and none of them are the independent companies they started off as. I just don't see Tesla being an independent EV company in 20 years. They will have sold out or merged with a larger company, or will at best be one of many OEMs for batteries and SDV tech.
In the 60’s the American car makers basically ignored the Japanese cars. They assumed that like the VW bug. The market for little cars would be a fraction of the market. Enter OPEC and the price of gas doubled in price.
The other thing to mention is that the Japanese were all over quality control.
Soon enough, American auto makers had trouble selling their tanks, and were forced to evolve.