Surely you jest.
All of the current supported platforms for Elite: Dangerous and the upcoming PS4 release are all designed to run on the x86/x64 architecture instruction set. The Nintendo Switch uses a processor based on the ARM 64 bit architecture instruction set. This would require the game code to be rewritten to make it compatible with the ARM instruction set, a major undertaking. Seeing as Frontier have repeatedly stated that they are not going to rewrite the entire game code so that it will run without certain game critical graphic API's (the reason Elite will run on the unix based Linux OS but not the unix based Mac OS is that Apple will not let several game critical graphic API's run on their OS), expecting them to rewrite the entire game code to run on a instruction set that is mainly being used by smartphones and tablets is probably an exercise in disappointment.
I don't think so. Switching to ARM 64 should not be a big issue. Most of the code will most likely be C++ anyway. Porting the part that is really depending on the instruction set (like atomic operations, SIMD operations etc.) will need some work but nothing too heavy. Then you have the OS differences but I expect them to have an abstraction layer for that and they would "only" need to port this layer. Most of the game code will be untouched.
The main reason why Horizons is not available on Mac is the lack of a recent graphics API that supports stuff like geometry shader.
The hard part of a Switch port would be that the hardware seems less powerfull than XBox / PS4. I doubt that the Switch could do the planetary stuff.
Edit: Of course the most work would be required to port the rendering pipeline. But this is something they have to do anyway.