I did some googling of LVDS to bring myself up-to-speed on this. There is a good
wikipedia entry on LVDS. I would assume that Tesla has used point-to-point flavor of LVDS since they probably did not consider adding anything else to the current bus. It is interesting that there is a multipoint LVDS option, but I doubt Tesla would have implemented this since it appears to be more complicated and therefore most expensive.
So in looking at this I think zax123's suggestion of some type of LVDS switcher/mux is the way to go. Ideally this would be a plug and play board with 2 input amphenol connectors and 1 output amphenol connector. There may have to be some sort of 12V DC to DC converter required to generate a 5V or 3.3V supply because I don't think the onboard supply for the camera is going to be able to drive the switcher/mux board. The switcher/mux board would then have to drive the power for the 2 cameras (which should be reasonable).
Then the next issue will be getting a proper cable from the switcher/mux board out to the nosecone. This has to be a proper cable. It seems that if Tesla has the cable from the dash to the rear camera, another of these same cables can be used to connect the front camera.
The last thing is how to switch from one camera to the other. Ideally there would be something on the touch screen to swap back and forth. But I don't know if we'll ever get a hardware output from the touchscreen for this. So we'll just have to see what people come up with for this.
Anybody have experience building LVDS systems?