In 2018, Elon said that Tesla was a dozen or so start ups having little correlation to legacy auto. Comments about my list, please:
Chip design
Supercharger design/build/manage
Motor and drive unit design/build
Insurance design/build
Sales
Autonomy design/build/manage
Factory design/build
Solar roof design/build
Utility energy storage design/build
Residential/commercial energy storage design/build
Auto design/build
Semi design/build
Battery design/build
Vehicle service
Future
HVAC design/build
AI interaction with physical world
EV ships/planes
Fossil fuel site remediation
Battery recycling (Redwood)
Think you nailed current 'startup' list.
The future: Well...
don't think Elon really likes planes. He seems to be focused on either ground transport or rockets. Maybe to him planes are are weird middle-thing, which will be obsoleted by a) cars in tunnels for distances of 0-300 km, b) hyperloop for distances of 300-1500 km and c) earth-to-earth starship launches doing continental hops.
He did however spend around 5 minutes on a recent Rogan pod explaining how a battery-driven plane could be very fast and energy efficient. So ... maybe.
I just think that he really likes solving big problems and ground transport and space is just ... bigger.
If Tesla and perhaps SpaceX does a collab re. planes I suspect a 20-30 person plane, because that can be done within ~2028-2030 battery tech as self-funded proof-of-concept.
Then quickly moving into 100-400 person envelopes, because that is where the volume is - and also where fossil fuel displaced really will move the needle.
Problem is that SpaceX spaceships earth-to-earth travel would soundly beat those planes.
However, it may be the case that public will be disinclined to accepting a lot of earth-to-earth starhip travelling: They are noise and are perceived to be dangerous. (Perhaps rightfully so: imagine the 2001 terrorist scenario played out with spacehips instead of planes...)
So, space ships may be allowed and popular for continent hopping on dedicated specialized platforms in the range of 20 places on earth (a handful per continent)
That would leave a large market open for quiet, effective, VTOL planes.
Also, being VTOL, that makes it possible to integrate with new dedicated air-strips: Not only can the planes themselves be fast and energy efficient. They could also be allowed to operate within city cores. This would make them extremely attractive, because then you no longer have to add 30-60 minute commute at each end of a current plane travel, but could instead add a few minutes.
(For sure, big corporations would transform their current heli-pads to handle VTOL planes also, making the air-strip commute an elevator ride instead of a car-trip)
I don't think Tesla would go into fossil fuel remediation. An important issue for sure. But Elons contribution is by solving current and future energy and transport. That is a very big thing. He does not also have to clean up the mess made by the fossil industry.
Battery recycling is a given. I think they are doing that already in-house - and are setting that up to scale alongside extreme expansion in battery production. With or without Redwood. Remember, that redwood have to support generic battery recycling which is limited due to being generic. Tesla can solve for specialized batteries, namely their own.
I don't think ship building are in Teslas future. But for sure, selling a kit of motors, batteries and control unit would be. Shipyards are pretty competetive. For sure, Tesla could eek out some innovations here also. But ... there are so many other opportunities were their innovation talents are better spent. Selling motor-battery-control-kits to shipbuilders captures a lot of the value add for electric ships.
I would add house building as a wild card.
When Tesla is ready to announce the widely anticipated HVAC for houses, the have 3 huge building blocks: Solar, Home batteries and HVAC. It makes a lot of sense to include custom sensors (temperature, moisture, etc) as well as house climate control. Now you have 4-5 building blocks of a house. Now, perhaps you can make innovation re. concrete or bricks (recall boring bricks). We know that Tesla has experience in glass: witness Tesla glass roofs and Semi and Cyber truck hardened glass.
Then it is getting to a point where you have most of what constitutes a house. From a vertical integration standpoint, it probably makes sense to just build the house fully, and do fast iteration and improvement, instead of spending a lot of time dealing with (and waiting for) sub-contractors not used to acting at the speed of Tesla/the speed of thought.
Tesla factory team is also beginning to accumulate a lot of experience handling the whole of planning and logistics of large construction projects.
House building is a big mouthful though. I would be surprised if they enter that space before 2030. But when (if) they do, I predict building whole neighborhoods or mini cities in one go because, again, being Tesla, scale is just very important.