There was an English guy who had been here for about 25 years who worked at the central library. He couldn't speak German, but slowly couldn't speak English properly either, and started speaking English with the German word order...

I believe that it is quite possible to live and work in the greater Zurich area and only speak English (depends on your job of course - but let's say as an English teacher). This is something that has changed even in the last 10 years. I have come across and Swiss plumber who speaks fluent English with a slight cockney accent. My dentist, vet and doctor speak English to me - despite my starting in German. I have heard people ask where something is in the Coop in English and been ready to help, only to hear directions from the shelf stacker to the correct shelves in English.

I used to have the trick of replying the beggars in the street with "Sorry mate, don't understand a word". Try that today and you are likely to get begged at in English...