I think a city is a great place to be in your 20s and early 30s, when its time to buy a house and have kids it becomes less attractive. Employees starting out in their careers absolutely need to be in an office to learn how to work, make a name for themselves and develop a raport with other employees. Similarly there are some types of people in some jobs (sales, marketing) who thrive off being in an office space with others.
WFH suits people who've got a fair few years ( >7) under their belt in their industry and have achieved a promotion or two. For those people now reaching the age where they're settling down, the ability to go to their parents hometown or a rural town they like and buy a house at a reasonable cost and start a family and put down roots there is a great and invaluable opportunity.
I think we'll see a lot more balance in future after this, but the city isn't emptying any time soon. certain people at a certain level in certain careers at a certain time in their lives will be at home and others may just work from home 1-2 days a week.