Certainly, this is one of the more innovative methods in which a city will be able to take to make sure that the old payphones would not be an eyesore, allowing it to keep up with the rest of the times with such a technologically relevant function. New York City has plans to transform half a thousand of its payphones by the time July rolls around, to deliver a total of 4,450 hotspots at the end of this decade, where each of these hotspots will be able to deliver speeds of up to 1Gbps.
I am quite sure that there will be some degree of ads, as well as throttling involved during peak periods, to make sure that everyone will be able to get a fair slice of the free Wi-Fi pie throughout the day.