You do know the term “company town” isn’t new and represents a problem if “the last century”, right? Well you should if you’re going to make statements like that. The fact is that most large companies are in pockets of heavy concentration.
Consider the name of a city once synonymous with the automobile industry. Consider what happened when that industry did branch out. Nobody wants to live there anymore, despite the land being ridiculously low priced. Pennies on the dollar would be higher than much if it is selling for.
What if the borrowing your cities have made based in the growth expectations placed in the tech industries there? I’d wager that if the tech companies there moved even a mere 50% of their jobs out to other places your cities wouldn’t have a high demand for that real estate.
Of course, they’d likely be facing bankruptcy in a few years because commercial real estate is not so desirable anymore, and residential rates would fall off sharply because why move there? Which would mean tax revenue would plummet.
Maybe, just maybe, Palo Alto wouldn’t be the next Detroit. After all, it has many thriving industries of not-large companies to sustain the appetite of the city council and people who vote for yet more “services” on the dimes taxed from those companies and the businesses that exist for supporting their employees, right?
But I suspect that if “big tech” in California did shrug, it would only mean a sunnier version of Detroit. Because that is what happens when you drive out the people and companies which are driving the desirability of the area out.