A lot of american metros are polycentric with their job markets already. That was one of the sells of suburbia: spread out and therefore lower the congestion that was bogging down urban areas at the time. There was a time when it was predicted manhattan would flood with manure in the future should horse traffic increase how it had been. Then of course the car came but still, these were concerns even back then. Someplaces instituted height limits to attempt to spread congestion too, especially done in europe where many cities today have denser urban sprawl but its pretty clearly capped at a height limit which forces it out.