Looking at the Tesla home page we see...a Supercharging station. It looks like the future.
What is Musk's goal? It is to save the world with clean energy. He has been very successful in kickstarting the cause with solar enterprises and compelling electrical cars, but what is next? Sure, more solar panels and more Teslas, but where is the REAL money and influence? It is in the fuel, not the vehicles. It would be better to be Chevron than to be Chevrolet, but it is really much better to be both.
The cars, then, serve as a way to get into the system and change it.
Maybe the real goal is to eventually operate many thousands of Tesla stations, located everywhere, capable of charging up any electrical vehicle and drawing on solar power that is available to Tesla at an advantageous cost. This would entice people to buy electric cars from whatever manufacturer. Musk has said he wants others to join with Tesla because his goal is to replace ICE cars with electrical ones. The lack of effective charging stations is perhaps now the most serious obstacle in this conversion process.
It could be that while we wonder about the details of the next Tesla, Mr. Musk may well be thinking beyond that with earthly ventures nobody suspects. And then there is Mars, but that is just the same game plan, isn't it?