Well, no, because the world at the end of the lockdown is not the same as the world before the disease started spreading. Some differences:
- People now know there is a dangerous disease and how to act and sanitize to mitigate its spread.
- Manufacturing and other logistics for medical providers have had the time of the lockdown to ramp up.
- Testing has had the time of the lockdown to ramp up.
- A vaccine is that much further along--which is the only viable long-term strategy.
- And most important, scientific understanding of the disease has had that much longer to develop.
Britain's "expose the youngsters" strategy has a terrible flaw, which is that we don't know if the disease is actually safe for young people! All we know are some basic statistics about messy data that was reported by overwhelmed medical systems with spotty testing.
There are reliable reports of a) some young people getting very sick from this disease, b) people who seem to have recovered going back into decline and in some cases death, and c) long-term lung damage among those who did not die.
The ideas that this disease is somehow safe for young people, and that contracting it once confers long-term immunity, are ideas that are yet to be scientifically proven. They are, for now, at best heuristics to aid triage.