To me it reads like another piece which just assumes that elimination via temporary hard lockdown + closed borders is obviously too expensive/difficult.
The German and South Korean examples are spurious. Germany's excellent contact tracing has been overwhelmed, because they opened borders. South Korea has managed to keep a lid on things with 100-200 cases per day, just within contact tracing capaity, with border controls contributing hugely to that.
That South Korean rate of about than 2 per million per day seems like a good mark for sustainability without lockdowns, in excellent agreement with Indie SAGE. You don't get there without tight borders. AFAIK there is zero evidence for a TTI program being able to deal with higher rates.