Except for the "railcity" shops in the major train stations; and the shops at zrh airport--all of these are open 365 days a year.
PS: Zurich's "railcity" has over 100 shops.
I did say "pretty much closed up" not completely closed up. The important thing being that there's a Sprüngli at the railcity in Zürich, and a couple more in the airport.
