Until we truly solve remote, there will be some concentration. And there's value to that as an employee. If your employer goes kaput, or you're stagnating in your career, or you have an abusive boss, there are plenty of opportunities available, and enough of them that one shock to the system won't break the local economy.
Of course, the flip side of that is that real estate values go through the roof.
Why would you go to the other extreme? There are hundreds of large cities around the US that could easily headquarter these big companies and not become company towns.
How small can a city be and have a healthy relationship with an employer of 25,000?
A company like Amazon will have some natural needs. No other city can really beat NYC for meeting those needs.
Not Chicago. Not Toronto. Not Raleigh. Not Jersey.
And certainly not Texas.
By air, land, and sea the best and most bountiful transport links to the rest of the US, or to the Europe-Africa side of the world, are out of NYC. Now maybe we can change that? But we don't seem to be working towards changing it. So as of today, and for the foreseeable future, NYC is the best hub.
Too many pundits are trying to shame Amazon into moving to a city like Detroit or a city in the American heartland. But these areas are unattractive places for obvious reasons and it seems like Americans want to deny it. Want to attract an Amazon? Invest in colleges, reduce business regulations, attract an international and diverse populace which would in turn create an interesting culture, invest in local secondary schools, and (I hate to say this) drop the social conservative politics. One of the reasons why London, Paris, New York, Washington DC, San Francisco, etc. are attractive internationally is the liberal populace and progressive culture - nobody wants to move to a socially conservative place.
I feel like the partisanship that America is experiencing is only going to accelerate. As of now, America's future is in the cities and for whatever reason, cities tend to generate a certain culture that many people in America's heartland don't want. They're going to have to be more welcoming of it if they want to attract these sort of businesses.
I also disagree that "nobody wants to move to a socially conservative place". CA, Florida, Colorado, Nevada are all examples of places that were conservative or still are but appear to be going through shifts as population moves there.
The real "losers" in this situation are heartland states without major metro areas, like most of the plain states and rural America.
DC is already woefully over staffed with overpaid folks living off of guaranteed tax revenues, I don't believe in the inherent productivity there, and just cynical enough to believe it's a means for AMZN to leverage political power and government contracts.
NYC is understandable ...
... but it would have been really nice for business diversity for that to go to so many other places. Chicago, Texas, Toronto, Raleigh, New Jersey etc etc.