This is all about the capacity of the healthcare system to handle the number of cases. The number of cases so far has been minimal compared to a normal flu season. For instance here in Illinois, so far the total cases has been 105 with zero deaths. That's not a lot in a state with 15 million residents. The infectious disease experts have models which show that if they can basically shut down society for the next two weeks, and keep the expected rise in cases from increasing at an uncontrolled exponential rate, that the other measures already in effect such as stopping travel from world hot spots, and people continuing to practice personal hygiene measures will prevent the curve of cases reaching levels beyond the healthcare system capacity. Once they are confident they have the capacity to handle the caseload, it would actually be beneficial down the road to ease up on the social restrictions. Quiet a few people will still get the virus as Trump hinted until July or August, but they will be able to treat the most vulnerable and not have to ration out care. Eventually the summer heat, and long days will make the virus less contagious, but by the time it happens a significant number of people will have had the virus, recovered and formed a significant population of those with immunity when the virus reappears next December or January. Even as things start returning to normal for most people in 6-8 weeks, the most vulnerable will have to be isolated as much as possible, but if they do become infected they will not have to be denied care.