In a theoretical world where millions of people are kicked out of their homes overnight, I don't think 2020 has many lessons that are going to be relevant.

In 2020 a lot of the transients left, but by 2022 they came back and then some. This had all kinds of whacky repercussions on rent prices for housing that was always used by transients and was always in the supply demand flux. Like it noticeably changed with seasons.

Long term New Yorkers did not leave the city.

What is happening instead is hundreds of thousands have been priced out of this city over the years only to be replaced with even more newcomers. Prices keep going up. "Supply and Demand" is a trick. Demand is for affordable housing and there is no interest to supply that. Plenty of supply on high end that will never ever trickle down.