What would the Germans have really gained by assaulting Switzerland? Switzerland's neutrality was useful in some ways.
Plus and invasion of Switzerland, depending on when it came, might have fractured the Axis since it probably would have ticked-off Il Duce.
IMHO Hitler would have been a lot better off if Mussolini had sided with the Allies. Hitler wasted a lot of time, men, and resources just bailing Il Duce out of predicaments which he stupidly got himself into.