To be fair, I'm almost sure that this would be part 2 of the plan. Nobody wants to do it and yet the technology is there for it. Just like the electric car at the time. Not to mention that Elon often talked about his desire to make a truck. If you look for the truck definition in wikipedia :
Truck - Wikipedia, the free encyclopedia that would make sense.
Here are my ideas on the topic (on top of what you already talked about). I know, some of the ideas are a bit far-fetched but who knows...I've been driving an electric car (S60) for the last 3 years which is something I never thought I would do!
For the Tesla Truck (Model TT), the tractor unit will have a relatively small battery (around 100miles) since the "real" battery (capable of doing around 500+miles fully loaded) would be in the semi-trailer as you already talked about.
The top of the semi-trailer will be covered with solar panels (hence the importance of the SolarCity acquisition) which means that technically speaking, you will never have to charge the semi-trailers. Just leave them in your warehouse parking lot under the sun and they will charge themselves instead of just sitting there doing nothing like they do today. Not to mention that the solar panels will also allow them to recharge the trailer batteries while in transit since the surface on top of a trailer is as big as the surface covered by panels on a house rooftop (if not bigger). In other words, I wouldn't be surprised to see a Model TT arriving at destination with still 50% charge left in the tank when traveling on a sunny day. This said, a plug will still be provided in case you don't have any sun in your area or if you have to keep your semi-trailers inside the warehouse for some reason. There is no need to charge the tractor unit either since hooking it up to a trailer will do the trick. Its battery is mainly used just to go from one trailer to another.
With "alpha" autopilot driving in place, the driver will only be responsible to bring the truck on and off the highway. There will be Tesla Truck Stations (TTS) on highways where the driver will leave the truck and put it in autonomous mode. The truck will drive itself to the next TTS where another driver will pick it up to bring it in town thus explaining why autopilot is so important for Tesla. This means that truck drivers will be able to stay with their families instead of always being out of town. This also means that once arrived at destination, just by switching the tractor from one semi-trailer to another, the driver will be able to send off a return trip right away. Fully autonomous driving might eventually completely replace the driver.
Semi-trailers will also have a motor (or more) for smoother acceleration, deceleration and of course : regenerative breaking. The tractor will need to be authorized to pick up the semi-trailer (via LTE connection) which means that stealing a semi-trailer will be as easy as stealing a model S (i.e. this will be very difficult to steal <- this clarification is destined for anyone working for Fortune Magazine as they tend to have some issues with obvious things...that is, if they managed to read until this point).
Last but not least, semi-trailers could be just rented by Tesla to customers which means that all they would have to buy would be the Tesla tractor (although the tractor could be rented as well). Main reason being that Tesla could use the semi-trailers to recycle model S,X,3 cells by using them in there. Same goes for solar panels reusability.
According to
The Real Cost of Trucking - Per Mile Operating Cost of a Commercial Truck - TruckersReport.com , gas costs are 39% of yearly trucking costs and trailer/cab is 17% which would mean 56% cost reduction right there. Autonomous driving will inevitably take over thus adding another 26% reduction (driver cost). Minor things remaining are maintenance costs which will be slightly reduced since the tractor won't need oil changes and for tires, Tesla just made a partnership with Hankook so I'll let you draw your own conclusions...
All of this to say that Tesla could easily add a trucking division with potentially 80% less costs than traditional trucking companies. This means that even if they were charging half the price of what regular companies charge, this new Tesla division would still be making a 30% margin. Sounds like a secret master plan to me... What do you think?
P.S. : Mr Musk, if any of the above could be part of a plan, just make a random tweet with words using the letters DTB (like Detrimental Targeted Bonification). People here will know what it means and this will remain (somewhat) top secret...
