[janedoegrrr]

High standard of living, excellent infrastructure (transport, finance, biz, gov), very good education (ETHZ, UZH, ZHAW, etc.), surrounded by amazing nature and landscape, very open and diverse (30% foreigners, all shapes and colors), political stability (don't underestimate this when you're thinking about 2050) and solid governance by direct democracy (ZH/CH)... the list goes on and on.

To not "pollute" this comment with various links the simplest way to get a few reference points is https://en.wikipedia.org/wiki/Z%C3%BCrich

Of course nothing's perfect and there's always room for improvement (obviously), and Zurich is also a place with a very high "transparency of costs" so people pay for most of these benefits (less by taxes - but more by rent, cost of living, etc.) but to keep it short: Historically and with recent and future developments it seems to be a valid candidate for being a good if not best place to live in 2050...