The endgame is to figure out the least cost sustainable measures of getting R0<1 until we have a vaccine or treatment safe enough for people in high risk groups to take.
> The endgame is to figure out the least cost sustainable measures of getting R0<1
The question assumes this has already been done: "single cases here and there, maybe even 0 cases".
It seems to me that the key question at that point is, if there are no active cases--everyone exposed to the virus who is still alive has either never developed symptoms in the first place, or has recovered from whatever symptoms they had and is now asymptomatic--is there still a risk of spreading the virus further?
It does not assume that - Wuhan currently has R0<1 and it did not and still does not have "single cases here and there, maybe even 0 cases"; R0<1 through a lockdown is a tested (in Wuhan) way to get from tens of thousands of cases to just tens of new cases per day and probably eventually to single isolated cases here and there. But we'd really like to find a less invasive, more sustainable set measures than what was done in Wuhan.
> Wuhan currently has R0<1 and it did not and still does not have "single cases here and there, maybe even 0 cases"
You're missing my point. I'm not saying that R0<1 implies "single cases here and there, maybe even 0 cases". I'm saying the converse: that "single cases here and there, maybe 0 cases" implies R0<1. Which is obviously true. And the scenario posed in this "Ask HN" question assumed "single cases here and there, maybe 0 cases", so if that implies R0<1, and it does, then the OP's scenario does assume R0<1, even though it doesn't say so explicitly.
The question assumes this has already been done: "single cases here and there, maybe even 0 cases".
It seems to me that the key question at that point is, if there are no active cases--everyone exposed to the virus who is still alive has either never developed symptoms in the first place, or has recovered from whatever symptoms they had and is now asymptomatic--is there still a risk of spreading the virus further?