It would take a prodigious “hail mary” for there to be any vaccine solution in 2020. That means there is no “exit strategy” until we have a vaccine(s) and/or the SARS-CoV-2 virus mutates into something less harmful. There are very good reasons why the lockdowns will need to be relaxed as we enter the summer months:
Financial cost
Mental health issues
Fading compliance (especially in the free world)
China has relaxed its lockdown and wave 2 infections have already commenced. This is unavoidable and why some restrictions will remain. At a certain point, restrictions will need to be strengthened again until the curve of infections and deaths pass their peak. The good news is that we are now better able to control these waves:
Containment. Germany and South Korea have shown how to flatten the infection and death curve with testing and contact tracing at scale (although both still needed a lockdown period during wave 1).
Treatment capacity. Specifically hospital/ICU capacity
Treatment improvements. Reducing deaths and the time in hospital.