In New York's Times, Michael Kimmelman is struggling with the same tradeoffs. I think he's in error about the origin of cities in the first place. "Historians tell us that cities emerged thousands of years ago for economic and industrial reasons — technological leaps produced a surplus of agricultural goods, which meant not everyone had to keep working the land." These "leaps" did not happen by magic. It's more accurate to think about a division of labour emerging between inventors and users of technology, and some combination of accumulated wisdom and pattern recognition led to more formal methods of ruling. He recognises, subsequently, the tension between good and bad contagions.
During the last century, millions of urban-dwelling Americans fled to the suburbs. Cities cleared old neighborhoods and replaced them with giant housing projects in vast empty spaces, arguing that crowded urban slums had become petri dishes for disease.Apparently gentrification is not relevant under current circumstances, but I digress. The politics, not so much: the people are where the agglomeration economies are and also where the large clusters of Wuhan virus contagion are emerging. The challenge right now is that the executive orders being issued by governors in the states with big cities might be destroying the positive contagions in order to damp down the unhealthy contagions. (That's speculation on my part, but it's something people are thinking about.)
But people have been moving back into cities even as technology has created myriad new ways of connecting remotely. Cities have become epicenters of new capital and creativity, because proximity breeds serendipity and strength, from which new ideas and opportunities arise.
Meanwhile, James Lileks is asking a pertinent question. "The more pertinent question would seem to be this: are you less likely to get the bug if you drive in your car to a large grocery store, or take a subway to a small, crowded one?" Once the plague passes, there might be plenty of social science opportunities just based on that.