Narrowing down a bit, I think it's the "downtown business district" that's on the way out -- and the accompanying high office rents, long commutes, etc.
My home is a place of rest and family, not work. Work happens at a dedicated location five minutes from home, on foot.
I think we'll see more of this in the future--mixed neighborhoods with a lot of residential space next to offices. What I think we won't see as much of, are huge office blocks very far from residential areas, where the majority of the workforce commutes an hour+ every day, each way, to work.
Central business districts were created by trains which let people move to suburbs; then hung around for a while due to concentration of office effects even as many commuters moved to cars. Interesting tho think about what transit looks like in a world without them. Public transit would need to move more away from the hub/spoke model, which possibly dooms new rail construction in existing car-centric cities; busses already go much more point to point with a lot more route options, but if you have less commuters, do those fail to maintain their current timetables as well?
The car-based world was supposed to work on suburban houses and out-of-town office parks - no expensive centralised land in a hub-and-spoke model, more like a grid.
But that kind of office park and lifestyle pretty much sucks. So I don't think city centres are in any danger. Turns out they're a useful way of organising socially even if they're not where the offices are.
Then why do cities built around cars - that never had trains - still have central business districts? i.e. the entire south & west of the US, pretty much.
To get the same concentration-of-offices effects in new developments, like I mentioned. But take a look at the size of those central business districts compared to older cities; look at the population of LA vs Chicago or Boston vs the size of their downtowns. (And LA is one that did have some streetcars for a while - Phoenix would be an even more extreme example of a big metro area with a truly pretty small central business district.) There was a lot less pull outside of certain industries - new industries like tech largely avoided ever going downtown much in the first place, preferring big suburban office parks.
So if you don't even need the suburban office parks anymore, do things sprawl out even more in places like Austin or Dallas that are surrounded by empty land (vs somewhere like the Bay Area which is hitting geographical barriers)?
You end up with city/county hall, local courts, then the lawyers, general contractors, banks etc all clustering around that. There's a natural clustering of resources that happens just from local government. It's not uncommon for the largest hospitals in the region to be near city hall. From there it just snowballs.
That said, I'm not sure why the neighborhood around San Jose's City Hall is so dead, it's very odd experience to go there
I've been reading that this change (hub and spoke to decentralized) was already a big effect of COVID.
I like trains, but an alternative could be electric buses, with Uber Pool-like dynamic routing. I'm not sure how the speed would compare, but, it gets pretty wild when you consider what's possible with mobile phones, AVs, and electric vehicles.
Moving offices outside of the downtown doesn't really help. The only visible benefit is less load on the city center (often tourist and historical destination).
It simple 2D geometry - if you live 1x from the office your commute is 20 minutes, if you live 2x from the office, your commute is 50 minutes, 3x from the office - 90 minutes commute, and so on. If you move the main cluster of the offices outside of the city border, then the commute time would change for people, for some it will decrease, for some it will increase. There would be exactly the same percentage of people living 1x, 2x, 3x etc. from the office, just the people would be shuffled between the quartiles.
My home is a place of rest and family, not work. Work happens at a dedicated location five minutes from home, on foot.
I think we'll see more of this in the future--mixed neighborhoods with a lot of residential space next to offices. What I think we won't see as much of, are huge office blocks very far from residential areas, where the majority of the workforce commutes an hour+ every day, each way, to work.