Schools and business's closing for 4-6 weeks is just the start. They needed some sort of end date, but there is no reason to think they will not continue to stay closed after that. Assuming Covid-19's infectability is about 2.5 (people the average patient infects), we need at least 60% of the population to be immune before new infections start to drop. Then most active corona patients will infect less than 1.0 other people. But that's just statistical data. It doesn't help you if you are one of the non-immune! You go out and interact with a crowd of random people, and you WILL get infected. But of course, we could then reopen schools but just for people with proven immunity. So 60% of normal attendance.

What everybody is trying to do now by isolating, cleaning, and social distance is to flatten the curve, so when that 2% gets to the hospitals they don't run out of respirators.