What actions do you mean? Move out from downtown to suburbs?
Without significant efforts to lower the R value (Aka the actions I alluded to; facial covering, social distancing, track and trace) - it’s only a matter of when, not if.
Minus a wonderful medical breakthrough, come find me next winter and let’s see how sure you are with such a quip.
Oh, and by then, a great expense to life, the cities will likely have reached herd immunity, but I won’t quip back, as it would be in bad taste.
I am hopeful that they will find that they are already well into the prevalence range of herd immunity. If so, that will put them, to use a turn of the phrase, ahead of the curve. It would also mean that they didn't really flatten anything at all, and they could suspend their shutdown immediately.
If they are only at low single digit prevalence, that would be truly very bad news indeed.
If they're somewhere in the middle, say, 25-35% prevalence, then they could get through it with one more surge, or draw it out indefinitely. In that case it will be interesting to see which path they choose.
If your hospital is empty, it’s because of the actions you took. Stop doing those actions, and your neighborhood will soon look like mine soon.
This thing of going to come in so many waves because humans seem to be incapable of not just learning from the past, but also the present.