Earlier quoted context omitted.
Yes, the problem is that our cities are already leveraged up to their eyeballs. At some point, the actual humans buying those bonds start becoming skeptical of the city’s ability to pay them back. LA currently has about a billion dollars of outstanding general obligation bonds (edit: but that does not include all their future liabilities). They're still rated AA, but I presume that is because the credit writing agenc…
Wikipedia says the GDP of the LA metro is ~1.5T. I think they could handle 1B in bonds. If they choose not to, it's not because it's some impossibility. Certainly not because roads are impossibly expensive.
My point is that much of what the city can tax has little to do with the city's GDP. Either the landscape of the city will have to change or the current taxation paradigm will have to change.