Earlier quoted context omitted.
> Finally, I'll be able to have one piece of hardware for playing at home and on the go. Until you're done playing both games, and then what ?
If it is like the Wii U older titles will also work. Games like splatoon, mario u (we love playing this as a family)and all older titles (via emulation) should be available.
The Switch runs on an ARM CPU. I doubt it will be compatible in any way.